Instagram will tell you who should be blocked

On a special page will be collected accounts that the user according to Instagram may want to block. This recommended blocklist is not randomly selected. The algorithm looks at whom the user has blocked on the social network Facebook, and searches for these contacts on Instagram. Matches fall into the recommended block list. 

The feature is expected to become available to ordinary users only when Facebook fully integrates Facebook Messenger with Instagram. Work on the integration of the messenger with Instagram is also being carried out by the Facebook team. The official launch dates of functions have not yet been announced. Presumably, the launch will take place before the end of 2020.