Password encryption

Moved a couple of old GoDaddy WordPress sites from their hosted server to a VPS. Updated all the Plugins and WordPress to 5.7 and php is now version 7.3.
Having problems with password encryption, looking at phpMyAdmin wp-user all of the existing encrypted passwords begin with the 4 characters $P$B. Editing an existing password in phpMyAdmin with Function MD5 produces an encrypted password not commencing with these 4 characters and is rejected logging in.
Is this a VPS setting problem or something I can amend in WordPress