This is what it looks like, and the red line is Chrome 74 rolling out:
So it looks like there's a Chrome change that made the emulated test slower on mobile.
I updated on to Chrome 74 beta some time ago on WebPageReplay and no alerts where fired, but I went and looked at my other testing setup and indeed 74 changes something. I updated to 74 beta the 11th, there's a jump there in user timings.
In first visual change it's harder to see because the instance I'm using isn't super stable:
but I think we can see a jump there too.
This is most sure a Chrome issue, but I wanna understand why we didn't get a WebPageReplay alert, so I'll look into that too.