It is only a year old. I mean how high of a priority can it be to not send your camera when your phone is locked or when you send the app to the background?
I absolutely want the Jitsi call to continue in the background while I quickly look up something in the calendar.
Though I have to admit I didn't try. I've only used it on the PC and Mac. I love Jitsi though, for some reason it's sooo much smoother video than MS Teams. Really adds a lot to the communication. I wish I could use it for work, but there it's Microsoft or nothing :P
The OS should block new uses of the camera if it's locked (sort of - face unlock obviously needs an exception), but killing existing ones seems rather aggressive and would create a new form of user hostility in relatively common situations.
For video I agree it doesn't make much sense, but in a web app world if you're recording video you may want to turn off the screen or do other things just like a computer. It should at least show you in the notification area.