I’d bet tipping inflation has a lot to do with that. Delivery can often times come out cheaper with the apps suggested tip than dining in with 20-25% being expected.
While I agree that the suggested tip percentages are getting out of hand, I personally refuse to follow those and I would be surprised if most people did. I tip the same as I ever did: 10% (or less) for bad service, 15% for decent but unremarkable service, 20% (or more) for good service. There's absolutely no reason to increase the percentages one tips just because the people writing the POS software are putting in crazy values.
You can tip any amount. You chose if tipping inflation would affect you.
US tipping is sick, and it is not fair to people who are involved in preparing your experience. Why only servers receiving tip? Why not the cook? Or cleaning lady? After all, dirty toilet will ruin your dining experience.