Drupal is moving to support utf8mb4, however, it is using utf8nb4_general_ci. Why take the time to move over to support it, and then not fully support it? Is there a specific reason, or just continuing utf8_general_ci from previous?
Would there be any problems with ignoring this and using unicode anyway?
Drupal Ticket: MySQL driver does not support full UTF-8 (emojis, asian symbols, mathematical symbols)
Here is a question on stack exchange which says really there is no reason not to use unicode now days and finally, on this question, it says “utf8_general_ci is a legacy collation that does not support expansions, contractions, or ignorable characters.”
I note that WordPress uses utf8mb4_unicode_ci.