TLS handshake fails with Alert (Level: Fatal, Description: Unknown CA):

[SST]

It seems I cannot post a full explanation of context so here is the short version. Ill add detail after.

Devices in field all suddenly unable to connect to GCP host.

Problem simplified to https_client sample with url changed to run.app and certificate changed to WR2.

Modem trace shows handshake terminating with TLSv1.2 Record Layer: Alert (Level: Fatal, Description: Unknown CA)

Given that I can connect with the same certificate and cipher using curl. Is this a bug? How should I proceed?

[SST]

Here is the curl line:

curl -v --tlsv1.2 --ciphers ECDHE-ECDSA-AES128-GCM-SHA256 --cacert wr2.pem --request POST --data 'test' https://run.app/

The certificate is here (It seems I cannot attach it):

https://i.pki.goog/wr2.pem