I upgraded this blog to WordPress 5.9 today, and all of my non-ASCII characters (such as typographical apostrophes or quotes or accented letters) got corrupted in the process. I’ve run into this before and I thought I’d fixed it, but clearly I still have an issue.
I tried to make a brute force “fix” and it made the blog look OK, but when I try to edit a page, I see the weird characters again.
So I shall write no more this evening and attack the problem again tomorrow.