Your inventory size changes so that there's always some empty slots!
Mods introducing new content into the game.
Play it your way.
Inventory size resets to default if i take my armor off, or if i update it in any way (putting items in the equipment grid) or using a jetpack so it just results in my whole inventory spilling on the ground 🗿🗿
why
That didn't happen before, so maybe an update broke it somehow? I'll test it later.
If anyone else comes across this or you want to see a possible solution, see this mod: https://mods.factorio.com/mod/qol_research