I am setting up Adsense in a site of mine and started by creating an ad unit with responsive ad size. As expected, ads 280px in height started showing up.
After some time, I decided those ads were too big and replaced the ad unit with a mobile banner (50px in height). Upon switching the code, nothing happened. The old 280px high ads were still showing up and console shows that the ad-slot ID belonged to the former responsive ad unit.
Thinking that this was a cache issue, I purged Cloudflare and also local browser cache but to no avail. I also tried using a new incognito window but that failed too. I disabled CloudFlare and cleared local cache again... but still the ad-slot ID was wrong.
Is this just a matter of waiting for Google to sort out things on its end?
Yes, it was a matter of just waiting.