Reproduction steps:
1. Download and open the project from the provided Google Drive link
2. Build and deploy the project to an iOS device
3. Make a call to the device (might crash on this step)
4. Decline the call
5. If the crash does not occur, repeat from step 3

Reproducible with: 2019.4.21f1
Could not test with: 2019.4.31f1, 2020.3.20f1, 2021.1.24f1, 2021.2.0b15, 2022.1.0a11 (lack of a reliable reproduction)

Reproduced with:
iPad Air 2 (iOS 14.3)

First lines of the stack trace:
Thread 26 name:  AVAudioSession Notify Thread
Thread 26 Crashed:
0   libEmbeddedSystemAUs.dylib      0x00000001b78fee8c InterruptionListener+ 618124 (void*, unsigned int, unsigned int, void const*) + 352
1   libEmbeddedSystemAUs.dylib      0x00000001b78fee88 InterruptionListener+ 618120 (void*, unsigned int, unsigned int, void const*) + 348
2   AudioToolbox                    0x0000000190be55a4 AudioSessionPropertyListeners::CallPropertyListeners+ 1054116 (unsigned int, unsigned int, void const*) + 596
3   AudioToolbox                    0x0000000190​​​​​​​c504c4 HandleAudioSessionCFTypePropertyChangedMessage+ 1492164 (unsigned int, unsigned int, void*, unsigned int) + 1136
4   AudioToolbox                    0x0000000190c4fb0c ProcessDeferredMessage+ 1489676 (unsigned int, __CFData const*, unsigned int, unsigned int) + 2244
5   AudioToolbox                    0x0000000190c4ee98 ASCallbackReceiver_AudioSessionPingMessage + 632

Notes:
- Video of the reproduction can be found in the edits linked as "Video of reproduction here"
- Issue can be reproduced by calling using FaceTime
- The reproduction rate varies, sometimes crashing after a couple of tries, sometimes crashing after up to 25 attempts