I think there might be a third-party plugin snap installed which has the certbot<2.0 constraint on it:
snap list
You can use
snap revert certbot
or if you know which revision number was working, you might be able to
snap revert certbot --revision=xxx
Once it works again, you can prevent Certbot from being updated again:
snap refresh --hold certbot
I'd really appreciate if you could let me know what plugins you have installed so I can contact the author to get this fixed. Thanks.