Hi, no limit at all, well just the Cloud Blueprints folder that is very very limited and recommended not to enable because it gave a lot of problems to members enabling that Cloud in game options.


EDIT
All information about the in-game Cloud added to the Pin of Bug Report sub forum :
Can't upload to Workshop - Workaround(s) 📌
https://psteamcommunity.yuanyoumao.com/app/244850/discussions/1/3267935171647013488/

+
Are you sure you lost Workshop subs ?

We can see all subs from the Workshop page and from our Steam Games LIbrary :

Workshop page
1 - Select "Your files" on the right of main front page.
2 - Select "Subscribed items".

Steam Games LIbrary
1 - Right click Space Engineers and select Properties.
2 - Select "Workshop".

EDIT
ME = I now have 381 Workshop Subs (from Workshop page / Your files) but there was more before because I've unsud to all outdated Mods not compatible with the new game version.

As always with these types of questions : How do you know half are missing? That means knowing the names of the mods you are subscribed. Check one of those. It could be that many of the missing ones are from modders who retired from modding and deactivated their mods.

Another thing to keep in mind :

-> Mods are not removed from our Modded saves.
+
I always save/upload a new created world having all Favorite tested working Mods to my Workshop, this way I can start new anytime I want and never lose my tested Mods list because they are all downloaded and installed automaticaly on loading the save.

=
We can resub to all Mods in the world edit settings if needed but I never lost any sub so far.

In terms of how I know I am missing them I had looked at the list the day before and then the next day the list was half the pages it was the day before.
As for checking if the mod or blueprint has been deactivated I have gone and found a few of the blueprints that vanished from the list and had to resubscribe to it.
It could be some sort of thing that is effecting me as there was a power outage the morning I noticed stuff missing so It might be something that was caused by that perhaps... but just to be safe I figured I'd ask if anyone else had an similar issues.

Me and my son lose power all the time and never lost any subs, the best you can do would be to report all information you have to Steam support and SE Devs,
-> one of them may find the cause for you.

I can tell it's not supposed to happen so there is something wrong for sure and reporting to Steam and the SE Devs will give you more Testers helping you.


+ Important for you To Do :

-> For now on you should do what I have shared in post #4 since you now know that losing Subs can happen in your PC.

=
Save all your Favorite Workshop Mods and Blueprints into Worlds saved in your Workshop, this way you will never lose any.

Thanks every one for the help I think I just figured out what happened and it looks like it's user error on my part. when I was subscribing to a list of blueprints I wanted to look at I must have hit the add and overwrite subscribed items which I was not used to so I think that is what happened. So thanks again for the help every one.