Yesterday's release (version 2.0.5 on March 26, 2020) contained a critical bug — oops. We've already released Sulu 2.0.6 today, March 27, and, hey presto: bug eliminated!
The bug only affected Sulu 2.0. Follow the Sulu 2 upgrade guide in our documentation and update your sites and codebases accordingly.
The backstory: We were very keen to solve the issue of Sulu ignoring default templates. We got overexcited and ended up setting the default template always ... yes, overriding everything, even for pages that already had a different template set. That's pretty annoying and also makes the system pretty unusable.
Long story short: We have fixed the problem (the right amount this time) in a separate PR and released version 2.0.6 of Sulu today!