character_set_client, _connection, and _results must all be utf8mb4 for that shortcake to be eatable.
Something, somewhere, is setting a subset of those individually. Rummage through my.cnf and phpmyadmin’s settings — something is not setting all three.
If SET NAMES utf8mb4 is executed, all three set correctly.
The sun shone because it is only 3-bytes – E2 98 80; utf8 is sufficient for 3-byte utf8 encodings of Unicode characters.