Yeah a major version number with no change-logs sure is very high risk. I wouldn’t install it on any critical sites until the basics are covered.
They’re known for not updating their changelog.
As well, the 2.0 bump is likely nothing major. They probably just do the annoying WordPress version numbering, where 1.9.9 then goes to 2.0.0, rather then 1.10.0.
Literally changed nothing other than the “Tested up to” https://github.com/mailgun/wordpress-plugin/commit/2d5f5f9099c128bdf7ab70fa838f1a9a5a455472
Per GitHub comments, it’s related to the plugin recently being temporarily closed: https://github.com/mailgun/wordpress-plugin/issues/180#issuecomment-2232831162
Oh great… Well, at least we know it is a safe enough update. But still… Speaking as a plugin dev myself, folks can update the tested up to without bumping plugin version numbers. I do it all the time. Like, literally, never have I had to update a plugin for feature changes or bugfixes alongside bumping the tested up to number. So, nice to know, but an annoying habit of this developer.