I don’t think so - I’ve not installed any myself and two of the test browsers (one on a device that worked, one on the device that didn’t) were freshly installed today with no changes made to them. The problem device is:
A Nokia X10 running Android 14 (a device that works is a Moto G23 running Android 14)
Display Size is set at 4 out of 5 (large, but duplicating that on another device doesn’t give the same problem)
Font Size is 3 out of 7
Language is English UK (same as another device that works)
FF is 142.0 from Google Play (same as another device that works)
The problem browsers on this test device are a regular FF 142.0 and a FF Nightly 144.0a1 on the “personal” side of the device and a FF 142.0 on the “work” side. Nothing in the MDM configuration should restrict Firefox (and the problem didn’t occur before today’s Discourse upgrade at c.osm.org) but that is a difference between devices that I might need to rule out.