this is unfortunately very common - I kept running very small ads regularly over many years (~10 years by now) and the % of bots has been steadily increasing, and Google doesn't really have any system to report those reliably to them. In fact, it's contrary to their incentives to investigate & fix these problems - unless they feel some pressure from competition...

From time to time, Google ads sales reps call me and are trying to convince me to increase the ads spend. I complain about bots, and none of them had any suggestion on what I can do to appeal it etc. I mean I can appeal on some specific instance, once - but there's no process to communicate back to Google the cases where I'm 99% certain about bots on regular basis.

And these bots get increasingly more sophisticated. They used to just click on ads. Then they started installing the app. Then running the app once and do nothing in it. Then they started tapping on the app screen & actually try to go through some initial app steps. When they do it in a spiky way, it's easy to detect them. But when they do it through some distributed device farms, below noise, it's very hard.