The “inground” labeled robots just have more attributes that generally serve inground pools better than their “above ground” labeled cousins such as :
longer cords (which help accommodate a deep end),
multiple brushes (more helpful for plaster/tile finishes),
& dedicated water line cleaning abilities (the ability to move horizontally @ the tile/waterline).
These attributes aren’t harmful to vinyl lined above ground pools, some are just often over kill & not all necessary.
Its a target market thing - not a safety rule.
I have a dolphin nautilus cc & it is perfectly fine for my above ground pool.
Having a vinyl liner, I didn’t feel I needed to pay the higher price for a next tier bot with 2 brushes or one that moved horizontally along the waterline but I also needed a longer cord than an S50/E10 (above ground version) comes with since my pool is larger. I also wanted the scheduling/automation mode options.
Just Get a bot that has the features you want/need & don’t pay for things you don’t need/won’t use. This can take a little research since there are so many similar models.
What issues are you having with your liner?