I have the opposite situation as this question. I received a call which Google marked as Suspected Spam Caller, but it was a legitimate call from a company I do business with. Can I report to Google that this is not spam so others are not confused? I selected the call in my history, and there is an option to report as spam, but not an option to report as not spam.
You missed seeing this Report a mistake in spam protection
If a call from someone you know is marked as spam, you can report the mistake.
Open your device's Phone app phone.
Tap Recent calls Recents.
Tap the call mistakenly labeled spam.
Tap Not spam.
Future calls from this number won't be marked as spam.
Another way to resolve this if the call is "potential spam" but does not show up with in red with an exclamation point and does not have the option to make as not spam, aside from adding the number as a contact, is just to simply call the number yourself!
I just had this issue, and tried adding it as a contact and removing it, but it became potential spam again immediately.
However, I then tapped the phone icon next to the entry in my calls list to dial the number, and after hanging up I noticed that did the trick and now the number in question shows normally!