Can someone tell me what this interference is

That is nothing unusual! I have noticed many times some SERIOUS interference patterns anywhere between top band and 40 metres. They drift across the band spread at leisure and there is nothing I can do to mitigate it. I often check on a web SDR, for example, Hack Green in the UK, and the issue shows up there as well, so much of the interference is not local to me. There is also much fixed frequency interference that can occur on top of an otherwise pleasant QSO, as if I don't even exist!

Having the most amazing ability to view large segments of the HF band all at once on my 6600M panadaptor display, one can easily view these nasty interferences. Probably over-the-horizon radar, who knows, but you can be assured that the perpetrators will never hold up their hands and confess the error of their ways!

All part of the fun of amateur radio.....

Mike G4GWH

-And here is the same thing on Hack Green at the same time. It renders the frequency absolutely useless!!