"Parameter is incorrect" when using runas with trustlevel after Windows 11 22H2 update

I had a script that needed to run as an administrator but then run a single command in a non-elevated context. I was previously doing it with runas /trustlevel:0x20000 program.exe, but after updating Windows 11 to 22H2 the command now gives the following output (running Notepad here as an example):

PS > runas /trustlevel:0x20000 notepad
RUNAS ERROR: Unable to run - notepad
87: The parameter is incorrect.

I've double-checked the trustlevel argument value and it appears to be correct:

PS > runas /showtrustlevels
The following trust levels are available on your system:
0x20000 (Basic User)

This happens for any app I try, not just Notepad or the one in my script. I've also tried it in Powershell 7, Windows Powershell (5) and from the command line, but no difference. Runas itself isn't completely broken, as I can do runas /profile /env /user:<username> notepad and it'll launch (after entering my password). I've also done an sfc /scannow just in case, but it's made no difference.

I'm currently trying to work out if there's anything I can do here or if the feature has just been deprecated in 22H2.