Playbar locked in TV mode ?

No. Actually I don't.
You can play music on your Playbar even when the TV is on. If the TV is on you will get a warning the TV audio will be stopped but id the TV is off the music will play straight away.

There isn't a way to change the timeout, but as Stuart said, you can play the Music immediately after, you just need to press an extra button on the controller when you play music confirming that you mean to turn off from the TV mode.

I think I see what the OP is saying. He would like, say, if the playbar was playing a particular radio station before he turned on the TV to watch..for it to resume that station after he's done using the TV. I think to do that would require you to select the music you want to hear on your controller again. It makes sense to have the TV sound from the playbar when you turn the TV on, but not so clear what to do when you're done watching TV. What if you want to go to bed after you're done? It would be annoying for music to start playing again on the playbar having to then go find the controller and turn it off.

I think I see what the OP is saying. He would like, say, if the playbar was playing a particular radio station before he turned on the TV to watch..for it to resume that station after he's done using the TV. I think to do that would require you to select the music you want to hear on your controller again. It makes sense to have the TV sound from the playbar when you turn the TV on, but not so clear what to do when you're done watching TV. What if you want to go to bed after you're done? It would be annoying for music to start playing again on the playbar having to then go find the controller and turn it off.

I thought that's what the OP might mean. But no other Sonos devices (Neither the Plays nor the Connects) behave in that way.

Sure it could be programmed but if you have any more than one other room how does the system "know" what to play? And if you decided it were to "resume where I left off" (Ie if I was playing something when the auto-start activated, continue that) what happens if the group is different or now not playing?

Recently I have the same "TV lock" issue: the playbar stays in TV mode. Before, it stayed for a limited period in TV mode, but recently it remains in TV mode after I switch of the TV. This means that I cannot start music pressing the button besides the playbar. I can only start music with the sonos app. I assume this started with a recently software update (version 8.2.2 build 39448021 is installed). I don't find any settings to limit the timeout.

Thanks @MarcSch
I have exactly the same problem. No solution found yet

It’s not a “problem” though it may not be how you want it to function. It is working as designed

I really not think that it is designed like this. After switching the TV off the sonos is waiting for the TV signal to appear again for ever (no timeout). The switch to the tv signal works always fine. This mis-behaviour is new since the last software update. I really would consider it as a bug not a feature.

However, the behaviour of the sonos playbar did change since a recent SW update. I preferred the way of working before, i.e. after shutting down the TV I can restart the previous playlist or radio channel by a simple press on the playbar button. I'm the only user of a smartphone at home. For my family, it's to much to start up a PC to be able to start music on the sonos. In other topics I also read some others prefer the current way of working (don't know why, mostly for them the solution was to switch on the autoplay), but also a lot prefer the previous way of working. A solution could be: make it a parameter below the autoplay, both satisfied!

TV lock: since the latest update I experience also that the TV timeout does not work anymore. My family cannot resume the radio music anymore with the side button of the playbar after the TV has been switched off. I like the standard old feature/function back: reason why I bought the Sonos to be replaced by my old receiver!! Please inform if you change a standard feature/function with an update and a solution to have the function working again by a downgrade: this is very very annoying. 😞