If that still doesn't solve your problem, here's another thing you can try. Put the PS5 into rest mode, wait a minute, then pull the plug from the wall. Wait 30 seconds, then plug it in again. It'll give you an error saying it wasn't turned off correctly, but that's good. This will force it to rebuild it's database which according to a lot of comments I've seen will fix the issue.

I know this sounds strange, so here's a link to one of the comment threads I found with other people talking about this and saying it works.
https://www.reddit.com/r/playstation/comments/qkoiae/comment/hx99h3a/?utm_source=share&utm_medium=web2x&context=3

I'm not 100% sure why this works, but I am an Electronics Engineer so I can make an educated guess. Since the PS5 is using the "other" folder as temporary storage, it's running into an issue where it's not correctly clearing it's cache. This tricks the PS5 into thinking the space is still full when in reality it's empty.
When it rebuilds it's database it realizes this and corrects it.