Try turning off the left speaker at the wall, leave it 30 secs then back on again and let it reconnect fully which could take a few mins. See if that stops the sporadic crackling.
It would also be worth turning off the Playbar at the wall too, and back on again, as it is from the Playbar that the surrounds receive their signal via a dedicated 5ghz wifi.
As it’s only when watching TV, also unplug and replug the optical cable between the TV and the Playbar too, ensuring both ends are seated firmly.
Failing all of that, go to the Playbar settings and Remove Surrounds. Swap the Ones over, and Add Surrounds again.