Crash on Review process, only on iPad (works on iPad Pro)

Our costumer app has been getting rejected and we've been trying to debug the issue with no avail, finally apple sent us a crash log since we couldn't reproduce it. It looks like it's Metal related but what and where.... I have no clue. Could be some post processing shader, could be geometry, could be some texture that got released and something is trying to access it.... Kind of hard to debug this, Can't get it to run on the simulator at all and pretty sure I wouldn't be able to reproduce this without real hardware. Runs fine on iPhone 7 Plus and iPad Pro 3rd generation, both on iOS 12.3.1

Crash is on iPad with iOS 12.3.1 (could reproduce on iPhone 6S Plus iOS 12.3.1)

The stack trace displays this:

Exception Type:  EXC_BAD_ACCESS (SIGSEGV)

Exception Subtype: KERN_INVALID_ADDRESS at 0x0000000000000000

VM Region Info: 0 is not in any region.  Bytes before following region: 4299931648

      REGION TYPE                      START - END             [ VSIZE] PRT/MAX SHRMOD  REGION DETAIL

      UNUSED SPACE AT START

---> 

      __TEXT                 00000001004bc000-00000001004c0000 [   16K] r-x/r-x SM=COW  ...app/cocobeach

Termination Signal: Segmentation fault: 11

Termination Reason: Namespace SIGNAL, Code 0xb

Terminating Process: exc handler [65344]

Triggered by Thread:  26





Thread 26 name:  UnityGfxDeviceWorker

Thread 26 Crashed:

0   cocobeach                        0x00000001009d6ddc GeometryJobTasks::ScheduleGeometryJobs(GfxDevice&, void (*)(GeometryJobData*), GeometryJobInstruction const*, unsigned int, bool) + 5352924 (GeometryJob.cpp:157)

1   cocobeach                        0x0000000100797bac GfxDeviceWorker::RunCommand(ThreadedStreamBuffer&) + 2997164 (GfxDeviceWorker.cpp:863)

2   cocobeach                        0x0000000100c08ec8 GfxDeviceWorkerAutoreleasePoolProxy + 7655112 (GfxDeviceMetal.mm:4144)

3   cocobeach                        0x0000000100798bb8 GfxDeviceWorker::RunExt(ThreadedStreamBuffer&) + 3001272 (GfxDeviceWorker.cpp:490)

4   cocobeach                        0x0000000100791618 GfxDeviceWorker::RunGfxDeviceWorker(void*) + 2971160 (GfxDeviceWorker.cpp:454)

5   cocobeach                        0x00000001009a1c7c Thread::RunThreadWrapper(void*) + 5135484 (Thread.cpp:87)

6   libsystem_pthread.dylib          0x00000001f08272c0 _pthread_body + 128

7   libsystem_pthread.dylib          0x00000001f0827220 _pthread_start + 44

8   libsystem_pthread.dylib          0x00000001f082acdc thread_start + 4