Thanks for your reply.
I'll give the SQL Native Client a try.
What I can confirm, is that the MySQL Community Installer 8.0.21 is not working at all.
I've tried several versions, not one is working.
I've analyzed the returned error message using WireShark, and I was able to get some more information.
Apparently, at some point, MySQL has altered their routine to authenticate against the database, which is causing this connection to fail. My guess is that the MySQL Community Installers only use the new method, and the old authentication method (as used by MySQL 5.0 and below) is ignored.