Yes, this bug can also be reproduced on the master branch, and the corresponding reproduction patch is attached.
I also considered comparing the 2pc.prepare_start_lsn and checkpoint.redo in ProcessTwoPhaseBuffer before, but this method requires modifying the format of the 2pc checkpoint file, which will bring compatibility issues. Especially for released branches, assuming that a node has encountered this bug, it will not be able to start successfully due to FATAL during crash recovery, and therefore cannot manually commit previous two-phase transactions. Using magic number to distinguish 2pc checkpoint file versions can't solve the problem in the above scenario either.
For unreleased branches, writing 2pc.prepare_start_lsn into the checkpoint file will be a good solution, but for released branches, I personally think using WAL record to overwrite checkpoint data would be a more reasonable approach, What do you think?
Best Regards
suyu.cmj