In the mean time I would recommend to fence off your growing areas in a way that it limits traffic through the fields. However I am aware that maybe the packing of the dirt happened while work was being done in the feilds.
Maybe this mod can help you fence things off. "Architect Expanded - Fences".

I’m having exactly the same issue, once I noticed I immediately started to limit access however it seems to be still occurring even as a result of harvesting. Has any solution been found?

Do you Terrain Rehabilitation researched?

Terrain Rehabilitation is from the Tilled Soil mods, not Desire Paths.

Use the PathAvoid mod (linked in this mod's description) to discourage your pawns from walking over fields - that way pawns will only walk onto the field to sow or harvest, which should limit packed dirt appearance in the fields. Also design some routes between your fields. Most of my fields are 5 tiles wide, with a 1 tile wide separator to allow moving between the fields without trampling the crops.
I've played with ~8 growers and the only times I noticed packed dirt appearing in fields was when caravans decided to wait in them, which was thankfully pretty rare.

The packed dirt tiles should return to the original tile over time, this may take a few days.

Hi, i use path avoid mod and i have the same problem. I have some packed dirt in my fields and they don't return to normal soil after 1 year, if someone have a solution to force it, i take it.

You can use dev mode 'set terrain' to set individual floor cells back to soil.

Suggestion to the mod author: not sure if this is easy or possible, but if it were possible to set a 'zone area' where this mod is forbidden from changing the terrain to packed dirt, that would help resolve this issue.

Oh thanks raydarken !

引用自 raydarken：

You can use dev mode 'set terrain' to set individual floor cells back to soil.

Suggestion to the mod author: not sure if this is easy or possible, but if it were possible to set a 'zone area' where this mod is forbidden from changing the terrain to packed dirt, that would help resolve this issue.

ive realised on this, dev mode the game will just revert changed tiles randomly back to packed dirt

Wait, and packed dirt reverts to its previous soil over time.

However it would be good if the packed dirt were not immune to terraforming, so a person could force converting it to other stuff. Of course a lot of people might not ever notice or realize that it does revert on its own.