Incorrect string value

I'm having trouble inserting some strings in the DB. My software versions:

• mysql: MariaDB 10.2.38
• php: 7.3.28

After I try to insert to the DB using PHP PDO, I get this error:

["22007",1366,"Incorrect string value: '\\xE2...<\/...' for column `DB`.`TABLE`.`data` at row 1"]

I tried setting the table collation to utf8mb4 but still the same error. I thin that the problem is caused by this emoji: 🔑. Any ideas how to solve this?