I second this error. Posted the link to my error log in the comments.

same error

XML error: <chance>0.01</chance> doesn't correspond to any field in type Option. Context: <li><chance>0.01</chance><thingSetMaker Class="ThingSetMaker_Count"><fixedParams><filter><thingSetMakerTagsToAllow><li>MU_ArchoUpgrades</li></thingSetMakerTagsToAllow></filter></fixedParams></thingSetMaker></li>
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch4 (string)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.XmlToObjectUtils.DoFieldSearch_Patch1 (System.Type,System.Xml.XmlNode,System.Xml.XmlNode)
Verse.DirectXmlToObjectNew:ResolveFieldForNode (System.Type,System.Xml.XmlNode,System.Xml.XmlNode)
(wrapper dynamic-method) Verse.DirectXmlToObjectNew/DummyTypeToHoldDynamicMethods:ParseAndAddComplexTypeToList_SharedBody (object,int,System.Xml.XmlNode,System.Type)
(wrapper dynamic-method) Verse.DirectXmlToObjectNew/DummyTypeToHoldDynamicMethods:ParseAndSetListField_RimWorld_ThingSetMaker_RandomOption+Option (object,System.Reflection.FieldInfo,System.Xml.XmlNode,System.Type)
(wrapper dynamic-method) Verse.DirectXmlToObjectNew/DummyTypeToHoldDynamicMethods:ParseAndSetComplexTypeField_SharedBody (object,System.Reflection.FieldInfo,System.Xml.XmlNode,System.Type)
(wrapper dynamic-method) Verse.DirectXmlToObjectNew/DummyTypeToHoldDynamicMethods:ParseAndReturnDef_Verse_Def (int,int,System.Xml.XmlNode,System.Type)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.DirectXmlToObjectNew.DefFromNodeNew_Patch3 (System.Xml.XmlNode,Verse.LoadableXmlAsset)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.LoadedModManager.ParseAndProcessXML_Patch1 (System.Xml.XmlDocument,System.Collections.Generic.Dictionary`2<System.Xml.XmlNode, Verse.LoadableXmlAsset>,bool)
Verse.LoadedModManager:LoadAllActiveMods (bool)
Verse.PlayDataLoader:DoPlayLoad ()
Verse.PlayDataLoader:LoadAllPlayData (bool)
Verse.Root/<>c:<Start>b__10_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

I am seeing this as well

XML error: <chance>0.01</chance> doesn't correspond to any field in type Option. Context: <li><chance>0.01</chance><thingSetMaker Class="ThingSetMaker_Count"><fixedParams><filter><thingSetMakerTagsToAllow><li>MU_ArchoUpgrades</li></thingSetMakerTagsToAllow></filter></fixedParams></thingSetMaker></li>

Possible Matches:
[Source: Royalty]
[File: D:\SteamLibrary\steamapps\common\RimWorld\Data\Royalty\Defs\HediffDefs\Hediffs_Local_Misc.xml]
[Source: Mechanoid Upgrades - Archotech]
[File: D:\SteamLibrary\steamapps\workshop\content\294100\3396928183\1.6\Patches\Patches.xml]

[Prepatcher, 0Harmony.dll] MonoMod.Utils.DynamicMethodDefinition.UnityEngine.StackTraceUtility.ExtractStackTrace_Patch1()
[Prepatcher, 0Harmony.dll] MonoMod.Utils.DynamicMethodDefinition.Verse.Log.Error_Patch3(System.String)
[Prepatcher, 0Harmony.dll] MonoMod.Utils.DynamicMethodDefinition.Verse.XmlToObjectUtils.DoFieldSearch_Patch1(System.Type, System.Xml.XmlNode, System.Xml.XmlNode)
[Core, Assembly-CSharp.dll] Verse.DirectXmlToObjectNew.ResolveFieldForNode(System.Type typeBeingDeserialized, System.Xml.XmlNode node, System.Xml.XmlNode parentForDebug)
[Core, Assembly-CSharp.dll] Verse.DirectXmlToObjectNew+DummyTypeToHoldDynamicMethods.ParseAndAddComplexTypeToList_SharedBody(System.Object, System.Int32, System.Xml.XmlNode, System.Type)
[Core, Assembly-CSharp.dll] Verse.DirectXmlToObjectNew+DummyTypeToHoldDynamicMethods.ParseAndSetListField_RimWorld_ThingSetMaker_RandomOption+Option(System.Object, System.Reflection.FieldInfo, System.Xml.XmlNode, System.Type)
[Core, Assembly-CSharp.dll] Verse.DirectXmlToObjectNew+DummyTypeToHoldDynamicMethods.ParseAndSetComplexTypeField_SharedBody(System.Object, System.Reflection.FieldInfo, System.Xml.XmlNode, System.Type)
[Core, Assembly-CSharp.dll] Verse.DirectXmlToObjectNew+DummyTypeToHoldDynamicMethods.ParseAndReturnDef_Verse_Def(System.Int32, System.Int32, System.Xml.XmlNode, System.Type)
[Prepatcher, 0Harmony.dll] MonoMod.Utils.DynamicMethodDefinition.Verse.DirectXmlToObjectNew.DefFromNodeNew_Patch2(System.Xml.XmlNode, Verse.LoadableXmlAsset)
[Prepatcher, 0Harmony.dll] MonoMod.Utils.DynamicMethodDefinition.Verse.LoadedModManager.ParseAndProcessXML_Patch3(System.Xml.XmlDocument, System.Collections.Generic.Dictionary`2[System.Xml.XmlNode,Verse.LoadableXmlAsset], System.Boolean)
[Core, Assembly-CSharp.dll] Verse.LoadedModManager.LoadAllActiveMods(System.Boolean hotReload)
[Core, Assembly-CSharp.dll] Verse.PlayDataLoader.DoPlayLoad()
[Core, Assembly-CSharp.dll] Verse.PlayDataLoader.LoadAllPlayData(System.Boolean recovering)
[Core, Assembly-CSharp.dll] Verse.Root+<>c.<Start>b__10_1()
[Core, Assembly-CSharp.dll] Verse.LongEventHandler.RunEventFromAnotherThread(System.Action action)
[Core, Assembly-CSharp.dll] Verse.LongEventHandler+<>c.<UpdateCurrentAsynchronousEvent>b__28_0()
[System, mscorlib.dll] System.Threading.ThreadHelper.ThreadStart_Context(System.Object state)
[System, mscorlib.dll] System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx)
[System, mscorlib.dll] System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx)
[System, mscorlib.dll] System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state)
[System, mscorlib.dll] System.Threading.ThreadHelper.ThreadStart()

It is [FSF] Better Exploration Loot https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3526957922
The error happens Mechanoid Upgrades - Archotech is loaded after that mod. Without combat extended for example, the Rimpy load order put this mod before BL. Wit CE or other mods which force Mechanoid Upgrades higher, the chance is there this mod is sorted before BL.

Here's what I did for a fix (reposted from my comment on the description):

I am not a modder, but I managed to fix the 'chance' error on my end. In the mod's Patches.xml, find the third PatchOperationAdd (xpath defName is "MapGen_AncientTempleContents"). Change <chance>0.1</chance> to <weight>0.1</weight>. I looked at the patch op below and it uses the 'weight' tag in the same spot the erroring op uses 'chance'. If you still find the upgrades from this mod in ancient temples from time to time, then it means this fix works.