It shouldn’t be. It should be mortared to cement board. It’s a pretty strong connection.
This. So much this. It is so easy to slip and fall, and anti-slip mats can only go so far.
I asked for ADA certified holds. My contractor used something the glues to the tiles, and assured me they are ADA approved. I would have preferred they were bolted to the beams, but this is what i ended up with.
They have been in place for several years, now, and i routinely grab them to get in and out of the high tub.