MTA says that "JSP support has been removed in Jakarta EE 10". That's only true with respect to its use as a Faces view technology. It is still very much part of EE 10 in general though.

https://github.com/windup/windup-rulesets/pull/800/files#diff-6f50ad65b0e6d53f03b7b8bf1ada507c5ec8857db36942123c426c6d69b3d39fR163-R180 done as part of the work on WINDUPRULE-894 does not limit the applicability of the rule the Faces applications.

I imagine this is the result of the discussion on https://docs.google.com/document/d/1uI9X0N74wsWFhGTI_37VsszNj04_KKM-tpSnz2B8b6Y/edit#heading=h.xm5n5v2kaqep. That document is only about Faces so anything on it is limited to the context of Faces apps, but I expect that limitation is easy to miss or not understand.