We've received recent changes [and check them out. [BR]
The situation is not corrected after changes. The fact is that the functions mbstrings must explicitly specify the encoding.
Therefore, we found an excellent solution of the issue and put the next patch mbstringsDetectEncode.patch
Attachment: fixed errors
Sorry, we're a little rushed and released a patch with little bug. New patch MbstringsDetectEncodeFixed.patch doesn't contain errors.
Thanks for reviewing the commit in #2769.
Since there are other mbstring issues with workarounds in place, I think it's time to refactor.