It does require a phone number to create an account. That’s the reason I do not consider it being private because at least in Germany a phone number can only be activated by using a personal ID card which it is connected to.
My app was suspended back in March just before Google updated their policy regarding to COVID. And my app was just being submitted for (my own) internal testing, didn't even made public.
One would've thought the change in policy back then was to allow Google to offer more clarity and fairness.
Note that, unlike OP's events app, your app was specifically about Covid/Coronavirus and serves no other purpose but to deliver Covid/Coronavirus information. I expect their judgement call is more plausible in your case than in OP's.
"Hi all! Just to clarify: All of JSTOR isn't public, but a lot is. We're happy to see your excitement. This content has been OA for a long time, but good to see awareness is growing. We are also working with universities & libraries who have been affected: https://about.jstor.org/covid19/"
- JSTOR
It seems what happened was that Google is following Apple's footsteps, allowing apps related to the coronavirus to be only from "recognized health organizations or the government".
I think this is fair and helpful in preventing the spread of misinformation. But Google should've been more transparent and tell developers the reasons for the app takedown. However, I'm still highly skeptical that suspension is needed as the data presented was purely factual and without misrepresentation.
https://signal.org/blog/phone-number-privacy-usernames/
Signal doesn't require sharing of phone numbers