You can disable the latest cutscene tweak with this option. Not everyone have that issue, so we will have to wait and see what to do about it. Try capping cutscene fps to 30 or 60, maybe it will be better that way.

FWIW another thread on Steam about this:

https://steamcommunity.com/app/12210/discussions/0/664957578230381716/

Using audio over DP, as I would imagine might be the thing there (DP or HDMI, that is). ExtraCutSceneFix=0 fixed it for them.

No idea about the numbers, but it's the first such thread I noticed. Sort of unfortunate if it's common: have been spamming FusionFix advise into the Steam forum basically daily.

Well, what else can I do? I can add a menu toggle for more convenient access to that toggle, but disabling it will return cutscene jitter. Obviously the solution is not ideal, but it somehow works [more often than not?]

If anybody can reproduce the delay consistently and willing to test a few builds, let me know.

Yes, a menu-toggle would probably be good, if this is not just rare -- and maybe if it's very non-rare, defaulting it to off. But...

I tried using DP-audio on my own setup (GTX970 to an Iiyama monitor) and I can't myself reproduce. Have also as said not seen the issue before on the Steam-forum so I'd assume it's not common at least

Update: reporter got back to the issue; appears it's not this ExtraCutSceneFix thing after all:

https://steamcommunity.com/app/12210/discussions/0/664957578230381716/?tscn=1750367620#c591774577804222495

The multi-second delay seemed to make it likely that it was; never saw that reported in another context than this one here, but I guess this may want to be closed again then.

Out of curiosity, I lowered the graphics settings and resolution, giving the game some performance headroom, and when running at ~300 fps, the cutscenes played almost comically fast, going out of sync very fast. But at this point the gameplay also became too fast. My point is, a) maybe these are related, and b) the gameplay speedup was claimed to be fixed in the other patch, so maybe this is something worth looking into. The test was performed in TBoGT, running on SteamOS.
EDIT: Weirdly enough, the base IV intro cutscene doesn't seem to have the audio desync issue, even when running at 144 fps, judging by the moment where Niko closes the trunk of Roman's Cab at the end of the cutscene, but in TBoGT, Tony's doorbell buzz is clearly out of sync even at 60 fps. I'll test this further.
EDIT2: I didn't know this issue was open when creating #756, my bad.

Yes, the game's general high-FPS issues are very well known. See e.g.

GTAmodding/GTAIV-Issues-List#112

I in the Steam forum for most any issue first of all advise explicitly frame-capping to under 60 FPS either with an external or refresh-rate+vsync cap or FusionFix' FPS-limiter before feeling it worth to even look closer.

If you went to 300 FPS by just lowering settings you are with not lowered settings still above 60, and will see all of the issues from that list (as it shows, 30 FPS is already a boundary but above 60 things start becoming impossible to ignore).