What really grinds my gears about the ad experience on mobile is how some ads will take over the comment section as well. Meaning that if you were reading a comment or a comment thread, the entire context is lost when an add pops up over it.

Once the ad is over you have to re-enter the comments, scroll back down to where you were, enter the chain, scroll down to where you were reading...

It's a torturous flow, but I suspect the "engagement" metrics look great on their dashboard. I can imagine a product manager somewhere is getting a raise after doubling user interaction with a single feature