Hello, Thank you for your answers.
In short: the work-around that I mentionned in the bug report is in place, and it works for me. The problem is "solved" for me and it does not look that any further effort to fix it in bullseye will work. Long version: Although it seems that ALL users of that library will be impacted by increased memory usage and CPU, it seems that there is no intent to fix this now: the maintainer does not want to fix it in bullseye as it is (presumably) fixed in bookworm, and LTS does not handle that package yet. Even when LTS takes over it presumably will not get fixed as it is not a security risk nor is seen as breaking the package completely. It does not seem from the maintainer's answer that even a carefully designed and tested patch would be accepted and applied in bullseye. It looks unlikely that LTS, when it takes over, would take in account a patch rejected by the maintainer. In short: the bug is now documented for all users that might experiment a show-stopper, with a few work-arounds described, one which does not require recompilation. That bug will not get a fix in bullseye's lifetime. Thank you again.