Source release of 10.4.21 signed by wrong GPG key

I need to download and compile MariaDB 10.4.21. From this page:

https://downloads.mariadb.org/mariadb/10.4.21/

I downlaod the source code and the checksum information, and try to verify the integrity with gpg. This tells me that I need to download this key: 0x199369E5404BD5FC7D2FE43BCBCB082A1BB943DB . But this key has no user ID, so verification fails. Somewhere on your site I read that this key is being retired, anyway, and that all files should be signed by a different key. Please re-sign the file(s) with the new key and publish the associated information. Thank you!