Connect error "SEC_E_ALGORITHM_MISMATCH" from Windows to Ubuntu server

The MariaDB connector on Windows seems unable to connect to a MariaDB server running on Ubuntu. Although the error (coming from MS Secure Channel) suggests a cipher mismatch, inspection of the ciphers supported on both sides shows 14 ciphers in common, one of which was selected by the server in the Server Hello.

The MySQL connector/C connects fine from Windows to the same MariaDB.

Inspection of the packets using Wireshark did not show an obvious problem. The Client Hello and Server Hello seemed ok (to a non-TLS expert). Stepping through the MariaDB Connector code on the Windows side also didn't show any obvious problem.

I've reached the limits of the debugging that I can do in this context. Are there other errors which MS will put into the "SEC_E_ALGORITHM_MISMATCH" return code? Are there any other known problems with MariaDB Connector/C on Windows? Any other ideas?

Wireshark files and (example self-signed) certificates are available.

To replicate:
(1) Have MariaDB 10.5.8 running on Ubuntu 20.04
In the config file have three lines
ssl-ca=/path/to/rootCA2.crt
ssl-cert=/path/to/sqlserver2.crt
ssl-key=/path/to/sqlserver2.key
add new user as
CREATE USER 'testuser'@'%' IDENTIFIED BY 'ChangeMe' REQUIRE X509;

(2) On Windows, use the command
"C:\Program Files\MariaDB 10.5\bin\mysql.exe" --ssl-cert=C:\Path\to\sqlclient2.crt --ssl-ca=C:\Path\to\rootCA2.crt --ssl-key=C:\Path\to\sqlclient2.key --user=testuser -pChangeMe --host=<ubuntu_hostname> --protocol=tcp --port=3306 --default-character-set=utf8

This should give the error
ERROR 2026 (HY000): SSL connection error: no cipher match. Error 0x80090331(SEC_E_ALGORITHM_MISMATCH)

Apologies if there is anything wrong with these settings, but I feel I have tried as many permutations as I can think of.

Thanks.