Did you reboot and then Trueplay tune your Sonos products? You may have already seen, for the majority, it appears the previous Sub audio issues mentioned in various discussion threads here, have been fixed.

See these two links too:

• https://youtu.be/r9noXA8qPNU
• https://www.theverge.com/2022/10/19/23413120/sonos-arc-sub-volume-trueplay-bugs-fixed

Also try power cycling all your Sonos products, solved bass issues i was having with the 14.8 update. 

Please kindly advise if I shall update the system first or power recycle first? And when shall I do the retuning? Thanks  

1.) Update > retuning > power cycle 

2.) Power cycle > Update > retuning 

3.) Update > power cycle > retuning 

Which one is correct?

I rebooted after. Don’t think a before would help much, but it also won’t do any harm. 

For the moment i tried everything, reboot, retune (several time) but the sub still weak. Actually there is more bass from the play5 when the is turn off. Even by setting sub to +7 its still soft it lost all is punch that it had before.

I’d suggest you generate a diagnostics and contact Sonos support. 

This is exactly the issue i was having.  When the sub was a on the bass disappeared, even though the sub cones were moving.  It was as if the Sub was trying to play high range notes. 

Have you powered off the speakers for a couple of minutes then tried again?

If not I’d do as @nik9669a suggests.

Hello, yes i unplug several Times the speaker but no changes

I’d call support then having submitted and noted your diagnostic number.

I will try to call and ask and let you know if there is any issue, maybe i was used to love the very high intensity of the sub ^^ but for sure it was much more powerfull before this update

I had that feeling too. But now my sub and play 5’s sound even better.