I think it is just a hoax with a regular iron sawdust or something similar and a magnet that hoaxer began to move under the table after initiating a call.

Phone could not align something into clear magnetic field pattern.

Don't know who is making that dumb videos about tha scary "graphene oxide" which have very weak magnetic properties and could not act like shown even from very strong magnet, but it looks like a campaign to discredit anything that not aligned with official narrative. Make a dumb fake video, push it to be spreaded by "conspiracy theorists" larpers who somehow forget to question everything in that case and you are in. Now it easy to make them look dumb.

Here is another example of same shit - https://conspiracies.win/p/12jdEGmgAS/this-is-how-graphene-reacts-when/

That's not the way, really. Question everything, especially things that looks too good for your theory. Otherwise you look just like all that "scientists" who don't bother to question all that official hoaxes they silently promote.