Switch to Bearer in Authorization header instead of OAuth in REST client

OAuth JWT is a different module altogether.
The doc you want is user-agent flow.
https://help.salesforce.com/s/articleView?id=xcloud.remoteaccess_oauth_u...

The recommended method is OAuth JWT, and setup is described here: https://www.drupal.org/docs/contributed-modules/salesforce-suite/create-... →
and here: https://www.drupal.org/docs/contributed-modules/salesforce-suite/set-up-... →

That's provided through salesforce_jwt sub-module

salesforce_oauth module is not really supported or recommended any more, so I'm hesitant to make further updates.

I'm not using the salesforce_oauth module, I'm using salesforce_jwt. The very first link in the module's Create a OAuth JWT Bearer Token flow connected app → document is the same official documentation what I linked in the issue description and it says that Bearer should be used in the Authorization header.

And the problem is not in the submodules but in the `salesforce` core module's RestClient as I also linked it in the issue description.

Huh, yeah, i see that now.
Weird that it's working at all then, unless like you suggest it's legacy support.

Seems straightforward enough.

I think the best would be to double check this with Salesforce support to ensure that this change not going to break connection for someone.