I own two TCL Roku TV's both equipped with Roku Streambars connected using the ARC cable.
Both are models #9102X
When turning on the TV's, they don't connect the Streambars automatically and usually don't start the connection until we have pressed a key on the remote. It then takes about 5 seconds to switch to the Streambar for control and sound. This is pretty annoying when trying to achieve a quick startup.
One of the TV's initially connected automatically but it now requires pressing a key on the remote.