I would like the new modern SLA flows (i.e. Power Automate version) to run under the context of the SYSTEM account, the same way they did with the "classic" SLA flows.

The fact about modern SLA flows running under the context of the last user who updated them has come back to bite us. A particular user account should never be associated with these SLAs, otherwise if this user account is deactivated and their license removed, then your SLAs will stop working for everyone. That's very bad.
Category: Routing/ SLA