Oh lots of things. There are always optimization’s and stuff, sure. Something may be proven redundant and the part might be removed or replaced with a better part, and when an old extension is looking for the previous part, it won’t be there and that will cause an issue. Updates are generally good. Personally I wait until the extensions and all the stuff I use are all up to date before updating, that way I can continue to enjoy making my game instead of waiting on others to fix things.