While going over this LinkedIn post about storing secrets in Azure Key-Vault and fetching them via Power Automate, a community member mentioned that that was all nice and well, but the content still shows in the 'Run History'.
Now, it is possible to hide all inputs and outputs for an action, but this depends on the Flow author knowing this facility exists and is an 'all-or-nothing' approach.
It would be great if this could be enhanced further. Some options:
Allow a special flag to be set when defining / populating variables. These variables can then be used as input in actions without the content of (only that variable) going into the run history.
Make it possible for the developers of connectors to specify 'fields' as sensitive, to prevent logging.