Thanks for the info, definitely not an older device then ;)
I'll see what I can do to fix that but can't reproduce at the moment I'm affraid (using iphone 12), maybe simulator will help.
Will also add some better handling of audio when the app goes in the background as that might be what causes bug number 2.
I have reproduced the pops everywhere I am able to manually trigger notes.
I was fiddling with the guitar tones, then opened from the background when the audio broke. I tried repeating that, but no repro.