Almost all my searches from the last days still show havfruen as a result somewhere. My pes anserinus above. Or "obos fellesgjeld" from a ~week ago which was when I noticed the pattern first. "monstera jord" gives lots of translated blogspam, and then a row of havfruen results.
Switching language on Google has basically no effect. Sometimes I want to find Swedish results for a thing with the same name, but no matter what I do I get Norwegian results ranked first. So don't think this is easily emulated from abroad.