Power BI Desktop should use the currently logged in account credentials for dataflow connections
When connecting to a dataflow in Power BI Desktop, the connection is cached like all other connections. Each connection persists the relevant tokens for their sources. However, when persisting a SQL connection, each database is cached separately, so different credentials can be used with different databases.
However, dataflows will only store the last connection to a dataflow, which makes connecting to dataflows in multiple tenants an arduous process of changeing the data connect options.
Also confusing is the fact that the account switcher control is unrelated to the dataflow credentials, leading to situations where publish shows one set of workspaces, but the dataflow connector shows another.
Having the account switcher credentials tied to the dataflow connection credentials would solve both of these problems.