https://git.cinelerra-gg.org/git/?p=goodguy/cinelerra.git;a=blob;f=cinelerra-5.1/thirdparty/src/ffmpeg-4.2.patch2;h=1862e19ca66a24a9e0b2f0d4946c291df09bbf61;hb=HEAD

should I try to post this to ffmpeg's ticket 7842 ? I don't have real BluRay player, so I can't test resulting files ...

Yes, please post. We used bluray/dvd creation a lot in the past and still occasionally so anything relevant to that is important to us. Bluray creation is EXTREMELY tricky and if not for the Sintel project ISO, gg would never have got it working because the documentation is all protected here in the United States.