Hello @Monkey-Spank, sorry to hear you have encountered this issue a few times now when launching the game.
We do not have a permanent fix for this issue, the skins reset because of a corrupted save file on your computer, but we recommend following our guide on this topic to resolve this issue temporarily > https://www.ubisoft.com/help?article=000061964
To help stop this issue from reappearing in the future, I also recommend doing the following >>
1. When the game is updating, make sure the update is not interrupted or its connection to the server, by closing down any other apps that you may be running in the background, on your PC or console
2. Disable any cloud save options you have enabled for the game, in your game launchers or consoles settings. Sometimes cloud saves can conflict with your local hard drive saves you may have and corrupt the file
3. (PC only) Make sure to make a backup copy of your local profile and save file routinely >
Ubisoft Connect > C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\savegames\\635
Steam > C:\Program Files (x86)\Ubisoft\Ubisoft Game Launcher\savegames\\1843