It's a cat and mouse game.
If that information is available, it can be gathered by adblockers to guesstimate how the video has been offset, and then you're back to square one.
If "clean" videos are still available (which they likely will be via youtube premium), you still have a reference of how the video should look, so you can start tagging suspicious sections as soon as they are categorically avoided by the youtube "timestamp fixer".
Sure, it will become harder as the frequency of mangled videos increase, worst case every single user will get their unique rendered video, but I think the performance hit on youtube would be immense, because AFAIK you cannot simply cut together separate video streams, even if they are aligned in encoding, resolution and everything beforehand, because it will break keyframes and create artifacts unless transcoded.
If the frequency is relatively low (say, one video per nation or US state) then adblock efforts can just adapt, the existing sponsorblock implementation could probably still work with some modifications.
I wouldn't call it a cat and mouse game because there is nothing from a technical point of view that prevents adblockers to use this information to skip ads. Unless YouTube gets completely rid of the concept of timestamps for their videos, they will always lose this battle.