Which sample rate do you use? Does 4800 sound better? When I try that one it seems to detune some of the synths.
I use 44.1kHz, but only because the sample library that I've built over the past 20+ years is at 44.1kHz.
Until recently, iPads used a default sample rate of 44.1kHz, but have switched to 48kHz with the 2018 iPad Pros & the 2019 Air 3 & Mini 5. Several music apps weren't updated, so they'll be out of tune.
Which iPad & apps are giving you these problems?