I don't know if you intend to provide any kind of support for such combination, so feel free to close if not, etc. In distro we still have some packages that use proj-7.* because their upstreams just didn't seem to work with newer versions.

The following tests FAILED:
         44 - testprojinfo (Timeout)
         51 - proj_test_cpp_api (Timeout)
Errors while running CTest

The issue is very well reproducible on different machines and different platforms, clearly bisected updating sqlite to 3.39.0.

I first thought I were hitting #3077 but the sqlite version is different and proj-9.0.0 seems unaffected.