However, we are using an older style official launcher. This is the case for the two additional accounts in my family as well. March 10th was supposedly the last day whereby you had to migrate to a Microsoft account, but I have not and still just use the old standard Mojang account without issue.
As of now at least I can still log in fine to my Minecraft account without a Microsoft account.
I use version 8 for this as well in Debian, but to run legacy Minecraft servers. I'm posting here to help clear up a few points that were brought up.