I've received a lot of 'possible spam' phone calls in last few days on my iPhone 8 Plus.

I added 'suspected spam' to my contact list when I got this phone a few years back. Two days ago, I started receiving several 'suspected spam' calls one after the other on my iPhone. I don't answer them. When I opened 'suspected spam' listed under Contacts, I saw several numbers that say 'flagged by Mr. Number'. HOW DO I GET THESE CALLS TO STOP?