Getting Invalid Signature algorithm error while generating token using client_assertion

Hello,

I am trying to fetch token using token api (https://{servername:port}/realms/{realm}/protocol/openid-connect/token) with following request body and the error is Invalid signature algorithm. I have attached a screenshot below for reference:

I have also added selected Signing algorithm in Credentials tab and added JWKS url in the Keys tab of the app (screenshots attached below):

I have also added keys in Realm settings:

Please can anyone help as it is very URGENT.

Regards,

Thanks in advance!!!