Converted Web 2.0 app will not compile with 2022r4.1 and MBS installed

I had to convert a Web 1.0 app to 2.0 and somehow managed most of the obstacles, one being that the interim step once chosen (2021r2.1) produced a weird incompatibility to 2022r4.1 when the WebContainerControls in their project format were tagged as such, not as WebPages like 2022 expects them …
But now the app won’t compile, with an error pointing towards MBS plugins. While I have them installed (23.0), I don’t use any of them in this project.
Fun fact is that 2021r2.1 will run the app with exactly the same set of plugins.
Any ideas about the possible cause? Yes, I did rebuild the cache.