Could be any of several things, there just isn’t enough information provided to be certain which it might be.
The first step I’d try is a network refresh, by unplugging all Sonos devices from power, then checking the router for updates, and rebooting it. Give the router a couple of minutes to come up, then power back up all Sonos devices. Wait another two minutes, then check the Sonos devices for updates, then test.
Next, I’d try a reboot of the TV set. First, check it for updates, then remove the power from the wall (turning it off with the remote is not good enough) for two minutes, then plug it back in.
Then I’d double check for possible sources of wifi interference, which might be impacting the ability of the PLAYBASE in communicating with the two Subs and the two PLAY:3s as surrounds.
For better knowledge, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, they get sensitive about GDPR.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.