Referrer Spam in Google Analytics
Look for, but don't be worried about, referrer spam in your Google Analytics
Over the years, folks have noticed strange entries in their Google Analytics. This is not real traffic, it is referrer spam. It’s a sneaky marketing technique by spammers and scammers to put themselves on analytics practitioners’ radar. They are usually trying to sell something like website traffic (by bots).
They inject the referrer spam by exploiting the Google Analytics API, which allows ANYone to write data to it if they have the GA identifier, which usually looks like UA-xxxxxxx. Attackers can usually just read that off of any website by “viewing source” of any webpage. This loophole will thankfully be closed in GA4; but that depends on how quickly users upgrade to the latest version. GA4 requires an API key to write data, which prevents this simple form of spam.
As a practitioner you don’t need to worry about this annoyance. You just have to filter it so you don’t count the fake traffic. This post has a good, step-by-step guide to filtering out this spam from your GA.
More examples below, from various sources, cited directly under the screen shots.
https://www.analytics-toolkit.com/referrer-spam/
NB: "filtering bot" in GA does not mean filtering the bad bods who pretend to be humans. Some agencies still believe, GA has an option "show me IVT, NHT, real HT" :-)