I stumbled upon this report when trying to solve my MediaWiki 1.31 utf8 issues with emojis. My MariaDB tables mostly had the utf8 (utf8mb3) encoding active causing the problem. I realized that the decision was made to recommend/support binary encodings of text column for MariaDB/MySQL only (containing UFT-8 raw data). Despite I would have preferred to switch to utf8mb4, I will stick to that recommendation and changed my columns to the up-to-date MediaWiki SQL schema.

For me, the following fix works (although I admit it's not a very general solution):