The module Salesforce OAuth aka salesforce_oauth is a submodule which implements a salesforce authentication plugin for interactive oauth API authentication.
This plugin has not been recommended for many years, and will be removed with the 6.0.0 release.
Sites still relying on Salesforce OAuth should switch to Salesforce JWT BEFORE updating to 6.0.0.
See instructions for creating a new JWT app in Salesforce and instructions for creating a Salesforce JWT auth provider in Drupal.
There is no automatic update.
The package lusitanian/oauth is no longer supported, and will be removed from composer dependencies with release 6.0.0.
Deprecation notices have been added to 5.1.x branch.
Any custom salesforce authentication plugins should be thoroughly tested and update custom code prior to deploying 6.0.0