It looks like your user name is being changed – and that is not typically allowed in WP.
So that behavior is specific to your site.
You need to find the code that is changing your username.
Can you still log into the site with your original user name?
I could not find the problem but I fixed it in a way.
It seems that only ADMIN user’s link is being changed every time I update it.
So I made a new user as a Moderator that I will be using personally and I will have Admin user for changing stuff on the site in the Background.