Word of a warning:
While I haven't done enough testing to be 100% sure, it seems that buying certain items (in my case, the lingerie/armour) at the store will cause your movement/walk keys to stop working. Even if you try to use the dash and the ranged attack to move (forwards and backwards respectively) and manage to change rooms or levels, it doesn't fix it. Additionally, if you get damaged while in this state, your character will get stuck mid animation and the enemy won't be able to continue hitting you (which means you can't even die to restart the run).
A wild guess: since it seems that movement and some of animations get disabled, maybe it's item(s) that are supposed to change the character's looks, but the updated looks simply aren't in-game yet, that cause this? I bought this item specifically to see if it'd become visible on the character, since her lack of any chest clothing, in a game featuring clothing destruction as a feature, was bothering me.
For now, it appears that the only fix is to delete the saves and start again. It doesn't look like you can (un)equip anything and when I opened the save file to see if I can just delete the item, the save structure is 4 pages full of numbered flags and cryptic variables, so finding the specific item ID would take a lot of time.