(Adding this note to the cloned bug) Note: If you take a look at the FTBFS bugs I reported yesterday:
https://people.debian.org/~sanvila/build-logs/202406/?C=M;O=A you can see that several of them are also a consequence of this change in po4a. So, I fully support that this kind of behaviour change deserves at least an entry in NEWS.Debian. Thanks.