@Oddný0 Presumably these are "inquiries," rather than "requests." That distinction is important, because you don't have to take any action on an inquiry except to write a reply (a simple "no" will do) within 24 hours. Requests, on the other hand, require a commitment of payment from the guest, and you must either accept or decline them.
As Emiel said, you can flag the spammers, but I don't think there's a way to prevent fake inquiries from coming through via the "Contact Host" link, as long as you have an active listing.
Airbnb could do more to prevent this by requiring members to complete their verifications before they can send inquiries, or by giving hosts the choice to automatically block contact from unverified profiles. The ease of setting up a burner account creates an obvious backdoor for bad actors to harass and scam other members on the platform.