Such as the fact that 'utf8' isn't 'utf8', 'utf8mb4' is... the feature was in testing as utf8 was being standardized and mysql used 'utf8mb3', and never updated the reference for 'utf8' for compatibility, even across major versions.
There's also the fact that collation on indexes for binary fields are case-insensitive if your default collation is, even if it's "binary".
Also, PostgreSQL has nicer support, imo, for JSON (JSONB) data, as well as a rich extension ecosystem.
MySQL's JSON data type, which exists since 5.7, which is quite old, is a solutely comparable to PostgreSQL's JSONB. (But don't be confused by MariaDB, which is a MySQL fork, where JSON is an alias to MEDIUMTEXT or something like that with little snytax validation)
Nothing like trying to do a select on a table/column that you know is there and getting an error...becuase the table/column was created with quotes by your ORM so it doesn't automagically get case in-sensitized.
It's maddening.