I like to play with robots and my sims often buy them from a business that one of my families own, but I am afraid to use them, because munchiebot, hydrobot and sentrybot spawn invisible NPCs when they’re turned on. This NPC doesn’t go away as long as the bot is turned on (and I can see them on the Teleport menu on Simblender), even when it’s not doing anything, so if I forget to manually turn it off before saving, it could damage my game.
So the question is: Is there a hack that automatically turns off robots once they come back to their station and if there is, where can I find it? I’d be grateful for any advice on how I could make it work.

It won't damage your game to save with them on; I've been using them for years with no problems.

I’ve heard that they sometimes can get unproperly deleted when you save (which is what I’m afraid of), is it a thing that happens only when you load a mod that resets the neighborhood like it is when a sim is talking on the phone?

The problems with the RC car were patched out many years ago; since then it seems that all of the EA NPC objects (caged birds, RC car, bots) work okay without risk of corruption under normal gameplay. If you are modding the game then the usual precautions apply (mark objects packages as read only, make frequent backups etc), but I've not had any issues and I mod my game heavily (and often have hood resets if I'm removing mods). For the record, saving whilst on the phone is fine too- worst case scenario is that you could get a sim stuck offworld if the game resets, but the FFS Debugger mod (batbox) can fix that. It won't cause corruption.

The NPC is there even if you never use the robots. Having them turned on just instantiates it on the lot. It's not dangerous to save with an NPC instantiated on the lot, it's totally fine.