I just installed MSFS 2024 SU1 after its release yesterday.
I started a flight with the A350 and got to the flight level. Then I decided that I wanted to fly elsewhere with a different A350. I exited that flight, chose another A350 with a different livery. Set up for another flight.
After spawning into the airport and getting into the cockpit, the Cold & Dark stage looks normal. Then I fired up the plan by turning on the 4 battery switches followed by the 2 external power. Very weirdly, the plane thought it was still flying from the previous flight. The plane's different systems during autopilot was on. Then there was a bunch of error messages and warnings.
Sounds like something needs to be reset before each new flight.