This further solidifies my point…from stereonet review of the holbo mk2…
The deck is intended to be used without a platter mat, although you could always experiment here. Any mat you try needs to be pretty thin, as the centre spindle (made from Delrin) is relatively short and stubby at only about 8mm in length. The deck comes supplied with a reasonably heavy record puck.
https://www.stereonet.com/reviews/holbo-mk-ii-airbearing-turntable-review
and from soundstage Australia…
The bearing’s centre pin is made of POM thermoplastic and “hard steel”. Holbo provides a logo-emblazoned, rather weighty and nicely machined stainless steel pop-on puck, or weight, which will pressure-flatten the disc onto the platter.
https://www.soundstageaustralia.com/index.php/reviews/652-holbo-airbearing-turntable-system-mk2
As I mentioned above, the mat isn’t needed. The only result you will accomplish is the uneven surface of the mat along with any other imperfections will prevent the puck from coupling and flattening the record on the platter.
My VPI table comes with a mat and the manual states it is to be used as dust cover. The VPI table includes a heavy screw on record clamp. At this point I’m 100% certain the rumble will be completely eliminated following the removal of the mat, irrespective of its material.

