Been watching this cycle for years - it's not just a feeling, you can actually track it. Pull your hourly conversion data and you'll see the same rotation pattern: one account spikes at 9am, another crashes at 10, then a third takes over by noon. the platforms seem to be throttling delivery in chunks to spread the spend.
What I've started doing is logging impression volumes every hour via a simple Python script (pulls from the API). Once you map those peaks and troughs to your own bid adjustments, you can start smoothing the roller coaster out a bit. It's not perfect, but it stops the whiplash
