Note that is dated October 2020. I've also seen YouTube videos from several PC gaming websites successfully test this.
Regarding the issue with Xbox series X here is an excellent video from Vincent Teoh ( HDTVtest ) explaining that
it's really an Xbox signal format(DSC compression) issue not really a fault of the Panasonic chip.
I follow quite a few AudioVideophile related forums & Websites which generally show high quality & accuracy, to that end, I would also like to see What HiFi present some real technical testing results in your reviews to go along with the subjective & colourful descriptive language which is useful but paints an incomplete picture when presented in the absence of technical information. I sent you an e-mail as well.
Le débit max acceptée par la carte est 32Gbps, tandis que la norme 2.1 est 40Gbps. Pour l'instant, seule la Xbox exploite pleinement la bande passante. Mais le contenu 8K utilisera aussi cela. Ainsi, Denon a trompé ses utilisateurs, cet ampli n'est pas compatible 8K. De plus les cartes ont d'autres problèmes, comme des micros coupures aléatoires sur les sources à framerate variable 4k@60i/s. C'est la catastrophe, et aucun remboursement n'est accepté. Mon ampli à 3000€ est au placard.
Now that I've translated your French. To begin with you miss my point and that is that Denon , Marantz,etc 2020 receivers will indeed pass video from games input from PS5 & Nvidia RTX30XX series graphics cards at either 4k@120fps or 8k@30fps, 8k@30fps only requires 24.48Gbps, Denon & Marantz support up to 40Gbps see video, so Denon, etc are not lying at all.
The Xbox uses DSC coding to output it's 8k supposedly at 60fps, this requires more than 48Gbs so Xbox must use Data Stream Compression to achieve this. It also occurred to me that Xbox series X must use DSC processing for 4K@120fps(Hence the Blank screen?) which seems entirely pointless when you look at the HDMI 2.1 specs. Your arguement is a really moot point as there is zero 8K content of any kind at this time and unlikely for the next few years. There are no games at all that are coded in 8k let alone 60 or 120fps. By the time there are your Xbox series x will no doubt have been supersceeded by yet another more powerful console. They've gotta keep the money wheel spining mate. Nothing at all wrong with your amp you're missing out on far more important things than 8k such as Dolby ATMOS & DTS:X also when the current gen 4K TV's catch up you'll have VRR, ALLM, QMS & QFT all of which your Denon amp supports.