How to get rid of malware popups?

Apparently picked up some malware, likely when viewing some of the interesting series of pictures on facebook via safari - something like "50 great pictures of ..."" ( i forget what exactly))

So now getting a series of brief small notifications in upper right and which last about 5 seconds

Eg

Potential Virus alert

Click here to remove virus

or

Renew your antivirus now

or

System error

Click here to renew your antivirus

or

Norton antivus 19.95 year .. click here ..

or Mccaffee: Virus found (5) ....

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I loaded Malwarebytes and ran it but does not find anything

persists after shutdown

runs when no browsera open

Etrecheck does not seem to find anything - report attached