Since commit 5d12b13b0b26bc58b02ee23c369da8b83240cceb, warnings are internally classified as errors which skip the check filters (see ClangTidyDiagnosticConsumer.cpp:324).
One usecase is particularly affected: you cannot selectively disable clang-analyzer-core checks, they are force-enabled because required by others. So enabling warning as errors will show new (and unwanted) errors !
32693 warnings generated. Suppressed 32693 warnings (32692 in non-user code, 1 with check filters). Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
33057 warnings generated. ... error: Called C++ object pointer is uninitialized [clang-analyzer-core.CallAndMessage,-warnings-as-errors] ... Suppressed 33054 warnings (33054 in non-user code). Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well. 1 warning treated as error
Related issue: https://github.com/llvm/llvm-project/issues/61520