Some places still have columns declared as utf8 instead of utf8mb4, and there's a special place in hell for authors of the MySQL general clusterfuck regarding encodings - it was all nice and great if you didn't care about anything other than latin1 or ASCII - go outside that before utf8 option and it was horror that even experienced operators managed to fuckup (I have a badge from a Google conference in 2017 with nicely visible effect of "we have mixed up one of the three separate encoding settings in MySQL and now you have mojibake in your badge").
And then there's UTF8 not actually being UTF8, which can result in total lockup of a table if someone inputs a character that does not fit in UCS-2 and now you need to recover the database from backup and preferably convert all instances of utf8 to utf8mb4, because fuck you that's why.
In fairness, reasoning about collations is like peering into the abyss. I get why they’re required to have so many levels of detail, and the Unicode Consortium has done a fantastic job, but to say they’re complicated is putting it mildly.
And then there's UTF8 not actually being UTF8, which can result in total lockup of a table if someone inputs a character that does not fit in UCS-2 and now you need to recover the database from backup and preferably convert all instances of utf8 to utf8mb4, because fuck you that's why.