Just FYI, had the same problem with our 2021 MY.
Tried:
Updated Tesla iPhone App; Rebooted car; rebooted Tesla wall charger; updated Tesla wall charger (it did turn out that it was way behind);
None of that worked... Charger worked perfectly when charging overnight (Scheduled departure), but wouldn't charge "on demand" for more than 5 minutes.
What worked:
Turned off mobile access at car;
Deleted all 3rd party apps;
Changed password on Tesla website;
Charging worked!
Added back mobile access and relogged in on Tesla app... so far the on-demand charging is working.