Not offhand, although I have my Era 300s set up as surrounds, and my Sub bonded to an Arc.

Nor were there any release notes that mentioned a change to the sound profile, although Sonos has said so in the past. Did you submit a system diagnostic, 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.

Yes — several users have reported reduced bass response after the October 17 update. Try recalibrating Trueplay and checking the EQ settings (bass and loudness toggles). If it still sounds weak, remove and re-add the Sub in the Sonos app or reboot your system. If the issue persists, it’s likely a software-side change — keep an eye on Sonos release notes or contact support for a fix.

I did all the above mentioned: trueplay, reboot, EQ, re-add sub4 etc. Still bad.

Then submit that diagnostic, and call in.