Few issues. One pretty serious.
1. I've uninstalled all my kart sim content on RC1. I cannot install it now. The cars are not available on the content list. Tracks are. Funny thing. They are no longer in the store as well (only T4 is). Which means that the list of content you own is not really based on what you own, but on what is available in the shop. This is serious omission. I can't install content I own.
2. Kinda related to the first one. You now see packs in the content. But not series based packs (which could be useful) but store side packs. Like (2022 Q3 content). Which should not be there. The content you don't own is based on store items, not packages (which you may own or not, regardless if they are still available, like it should).
3. The new package manager still can't handle updates properly. Old versions of store items remain without any external dependency (local package, workshop package or skin). I can go to ModMgr and uninstall them easily, but it seems it's still bugged and some package dependencies are still not solved properly.
4. The contentIndex.idx is not updated when using ModMgr which causes mayhem when installing local mods using ModMgr. Packages are installed, but the UI thinks they are not and it tries to uninstall them when you start the game. Is ModMgr obsolete? Cause you made it unusable for installing content with this update.
EDIT: heh, even if I install packages in content manager inside the game they do work, but the game uninstalls them the next time I start. contentIndex.idx was not updated. Something is really bugged here.