The mobile version of Minecraft Bedrock is always maxed on 60FPS. This prevents the capabilities of a smoother experience on higher refresh rate devices (ex. iPad Pro M1 120hz). Instead, higher hertz devices end up having a choppy inconsistent 60 FPS, which feels less smooth than an actual 60hz device. On 90hz devices, 60hz isn't evenly divisible by 90hz, so it pretty much guarantees a choppy feel for the game. Though for some reason (based on testing on a 120hz iPad Pro, which is evenly divisible), 120hz also feels choppier than a normal 60hz device.

Ways it could be implemented: 

Because not every <60hz mobile device is capable of higher FPS for MC, I think it should be an experimental option (Maximum Framerate). It should be a slider like in Java Edition, though the highest the slider should go is the detected refresh rate of the mobile device. I think the default option should be adjusted at 60FPS based on hardware limitations for specific <60hz devices.

PS: I'm aware that there are resource packs that do have a maximum framerate slider, but it does not work, as something other than the data in options.txt is limiting the framerate.

If this report seems like more of a suggestion than a bug, let me first explain something. There are suggestions for this already for a long while now, but nothing has changed in the slightest ever since those suggestions were made. Also, it is somewhat a bug because it is a limitation based on outdated code (I'm pretty sure that's why) that prevents anything higher than 60 FPS.