6.85 what kind of wizardry is that. ( Are you sure there is not a 1 missing at the front of that )
Black Magic I tell you.
Patch-sizes have nothing to do with compression (or almost not). This is pure packaging. E.g. if you have many small packets, you just replace those small packages. If you have just a few big packages, you must replace the big packages.
We no longer (since ages) in a time where a patch is a little program that replaces parts of other files or something like that. Even if a small "ini"-file is updated and this is inside of a 8GB package, the 8GB package get's replaced nowadays (if the program didn't have a logic that first looks in other "patch"-files for replacements or something like that). But as internet-speeds get higher and higher (and storaged doesn't cost much) this makes no sense. But having smaller packages like the PS5 uses for it's game (better streaming) the patches get smaller because they only consist of the small packages that were altered. For xbox consoles, still the "old" build-pipelines are used because ... why not they are working and you can deliver the game to 4 platforms at once
. E.g. you can download the game on an HDD/SSD (whatever) and also play it on the xbox one. Those are just the same packages. And this will go away over time. PS5 has the advantage here that it has it's own build pipeline because if it wouldn't have it the game would be limited to PS4 Pro feature set so they had to adapt to the new SDK for the PS5 version.
In the end it is only relevant how big the game is after the patch. And this game is not even compareable, because xbox still uses the "old" pipeline. We still have to wait for current-gen only games in the future to really see the difference.
The only example so far on xbox side that comes to my mind is Gears 5 that got a new build-pipeline epically (MS seems to use that game over and over again to test their tech).