Critical Site Health Issue after WordPress Migration

This might not be the issue, but I would install the All In One WP Security & Firewall plugin by “Tips and Tricks HQ” and use that plugin the check your file and directory permissions. Often times file permissions or also file ownership gets messed up in migrations. Seeing as you have deleted all plugins and are running the stock twenty something theme, it might be giving you a false error. Also, you could try reinstalling WP Core. That might help too. Just a thought.