On my Apple TV 4K remote, the FF speed maxes out at about 2x the FF jump speed in Settings if I hold down the FF button on the remote.
On my ONN Pro (set to the same 30 sec FF setting), the longer I hold the FF button down, the faster it goes up to what appears to be jumping 10 mins forward every 3/4 sec or so.
I was time-shifting an NFL football game earlier today and on my Apple TV device it would have taken me over a minute of me holding down the remote's FF button in order to get from the beginning of the recording to the start of the second half. On the ONN Pro, this took less than 10 secs.
Is there some hardware difference that prevents the Apple TV device from doing the same FF behavior as the ONN Pro when pressing FF? I have the Apple remote scroll pad disabled, so maybe that has something to do with it?