Sonos devices are not in a position to fix a delay in receiving the ‘processed’ audio from a TV - All the Sonos Home Theatre devices (should) do play the audio as soon as it arrives, with virtually little, or no, buffering involved and no transcoding. The issue is what is happening to the audio before it arrives at the connected HT device that is causing the delays here and lip-sync issues?

Some TV manufacturers have resolved these type of issues in a variety of different ways by increasing the abilities of their TV models with faster processors and introducing such features as lip-sync tools (usually available in the TV sound-out settings), but most TV brands seem to now be using ‘audio pass-through’ for connected devices like the PlayStation, XBox, Apple TV, Fire-stick etc. so that the TV itself, effectively lets the audio bypass (pass-through) the TV, without it being processed.

If your TV is not able to do these things with its connected devices, then I suggest perhaps looking at the option of using an audio splitter/extractor, which takes the audio from such devices and extracts and splits it off to the Sonos Receiver and by-passes the TV/ports altogether and eradicates any delays usually caused by the TV/Processor/Ports.

There are numerous TV audio extractors and splitters mentioned in many threads on this forum, but if looking to pass-though (split/extract) ‘Dolby Atmos’ audio to the Beam (gen2) then I would suggest perhaps looking into the option of using the HDFury Arcana, or other ‘similar’ audio extractor/pass-through devices that can handle that type of audio format. See below link:

https://www.hdfury.uk/product/hdfury-arcana/

I hope that information assists and gives you a way to resolve the lip-sync delays, but note the Arcana will only work for the connected devices, like your PS5, or cable TV box. It will not assist with any audio delays arising from any of the Apps built into your TV.

Some further things to maybe mention, is that reportedly ‘some’ TV’s ‘may’ occasionally provide better lip-sync performance if the Sonos HT device is connected to the TV’s optical port (using the adapter provided with the Beam) - but that will of course mean no HDMI-CEC TV control and it will limit the Sonos HT to only being able to playback PCM/Stereo/Dolby 5.1 audio and no Atmos, nor LPCM (multichannel) audio, but that might be something to also try/consider aswell, even as a temporary interim option, or you could of course see if limiting the TV playback to PCM stereo works okay with your TV processor by switching the audio-out codec to PCM stereo only.

Hope that info. provides you with some options to consider.

Sorry but this is very weird. I just bought a 499€ soundbar and I need to buy a device to correct a delay of this 499€ soundbar? 

I tried with my ps5 and setting on dolby (utilising atmos) it's almost impossible to watch/listen: the delay increase a lot more than just utilising tv channels.

If this is normal i will consider to resend back the product

This is to fix the delay in your TV set sending out the signal properly, it has nothing whatsoever to do with any delay in the Sonos. 

The audio delay is not (usually) the fault of the connected ‘soundbar’ - think of the Sonos Beam itself, as just being a receiving speaker device, that plays the audio as soon as it is received, with very little, or no buffering involved.

The issue therefore ‘most likely’ lies with the Television, its connected peripherals, or the cable connections in-between, being unable to transmit/send Dolby 5.1/Atmos audio quickly enough, along the route to play the audio in sync with the video on the TV screen.

If there are no pass-through options showing in the TV settings, then the TV is perhaps trying to ‘process’ the multi-channel audio and is unable to do that quickly enough.

Try changing the TV codec to PCM and see if the TV can handle just the two stereo channels in a more timely manner. If it can, it will help show the Beam is working fine and that the TV is having trouble processing the Dolby 5.1 (atmos) audio in good time. You will likely encounter the same issue with another brand of HDMI-Arc/eARC-connected Dolby Atmos Soundbar, not just the Sonos Beam.

I would perhaps look further into the ‘sending/handling’ aspects of the multichannel audio, rather than blaming the Beam receiver, at this early stage, as the audio delays are ‘usually’ not the fault of any connected Soundbar.

Im having this same issue with my XBR-55X900E and PS5. It didnt notice much lag when I first got my Beam Gen 2. Today I tried my PS5 and the lag is very noticable. I was looking to replace the TV for about a month now and this is the last straw. I was having issues running my PS5 in HDR in the HDMI 3 port of the TV as well. Im getting the LG C1, hopefully I get better results.