Interesting!
If it happens only over 50 or so. I would rule out crank since we're using a cvt.
Engine rpm's high at low speed as well.
On the gas when it happens or under load at a given rotational speed of the drive train.
If you let off the gas it goes away the speed is still there. So under load it is.
Conversions has a higher rpm and applied power than a standard pilot. If these issue bare cropping up after a little time I would say it's a wear issue. If it had the issue from the start either it is already wore or something is out of balance or alignment.
Then there is tire choice and terrain. Rolling load verses pulling load. Sand tires would be pulling load. Standard tire would be a rolling load.
So step one change tires and see if it gets worse or better. Then ride on payment then dirt and then sand and compare.
If happens on pavement look for an out of balance issue somewhere in the drive train.
Last check the distance between drive and driven and run out on both clutches.
It may be a frequency issue which is not good on parts.
Most of our axles are pretty worn and trans have a lot of wear.
The only other thing on the drive side would be the drive clutch. I would check there first and make sure all is good for your type and set true on crank.
Some first thoughts.