It's the same for me, it happened last week with the last update. 2 of my 6 accounts that i have been using for years now started to ask for login and password and then i have an error. I removed the account and I cannot add it anymore, it gives me the same error even if i don't provide the password, the error comes before that.

Are they Google Accounts?

Google needs to be set to "Allow 3rd Party Applications", otherwise corrrect password or not, you're not getting in with Thunderbird. May be same issue with other providers. It recently happened to me, and that was the problem. I had to re-enable the 3r party setting.

Go to;

https://myaccount.google.com/security?

Look for "Your Connections to third-party Apps and Services"

See if Thunderbird is there, and if not, see how you can add it.

Are these Google Accounts?

You may want to go to your Google account - Security and look for;

"Your connections to third-party apps and services"

Make sure you are allowing access to Thunderbird because correct password or not, you won't get access via Thunderbird. It happened to me a few weeks ago. Once I added Thunderbird (AGAIN), I was back in.

Duplicate - Moz had a hiccup (Server Error)