A bit of a challenging issue, but I had a point at which something (not sure, but may have been dbPowerAmp to 20xx release) where previews and icon previews of pretty much all video files stopped working. Physically, the registry entries for the icon/preview handler seems to have "got confused" by the upgrade installation of one of the programs. The three programs that are suspect as being the cause for this are dbPowerAmp (latest), Magix SoundForge Audio Studio 16 and VLC Media Player (Windows Store install of the full desktop version). This is all running on Windows 11 22H2 (Insider Preview Release Preview ring) and I submitted the issue to Microsoft as I first suspected a Windows Update or an update to Windows 11 Media Player (Groove), but then found one of my PCs not showing the problem (and did not have these three pieces of software). I followed this up with the following (which provides more info on the issue and my fix):

"I have now managed to identify and fix the issue - the registry entries for the video files had got 'corrupted' with a series of apps changing them to the point at which they lost the original backup settings used for normal use. The specific apps in question seem to have been a combination of latest versions of VLC (from the Windows Store), SoundForge Audio Studio 16 and maybe also dbPowerAmp. Having grabbed the registry entries from another PC where the icons were working (with VLC installed but not SoundForge or dbPowerAmp) I was able to reapply these entries which fixed the issue - then uninstalled both VLC from the Windows Store and SoundForge, reinstalling the VLC from their site (so can install WITHOUT Explorer extensions) and latest version of SoundForge, making sure Explorer extensions were not installed - and this seems to be working OK now. Will feedback to both VLC, dbPowerAmp and Magix about this issue."

I know that it is quite a complex issue, but if all of you could check on the way the preview handler registry entries are managed, to make sure that other third party handlers being installed/removed don't break the original installation and always keep the backup of the OOTB handler, this should at least mitigate the problem if not completely fix it.