I get a crash without any code, just by running gunicorn. It looks like a bug in gunicorn.

---
$ python3.8 -m venv env
$ env/bin/python -m pip install gunicorn
(..)
Successfully installed gunicorn-20.0.4

$ ./env/bin/python -X dev -c 'from gunicorn.app.wsgiapp import run; run()' foobar:app 
...)

[2021-01-11 16:14:11 +0100] [32107] [ERROR] Exception in worker process
Traceback (most recent call last):
  (...)
  File "/home/vstinner/z/env/lib64/python3.8/site-packages/gunicorn/app/wsgiapp.py", line 39, in load_wsgiapp
    return util.import_app(self.app_uri)
  File "/home/vstinner/z/env/lib64/python3.8/site-packages/gunicorn/util.py", line 358, in import_app
    mod = importlib.import_module(module)
  (...)
ModuleNotFoundError: No module named 'foobar'

[2021-01-11 16:14:11 +0100] [32107] [INFO] Worker exiting (pid: 32107)
sys:1: ResourceWarning: unclosed <socket.socket fd=5, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('127.0.0.1', 8000)>
ResourceWarning: Enable tracemalloc to get the object allocation traceback
Debug memory block at address p=0x55cfa92154a0: API '1'
    3271705103877500672 bytes originally requested
    The 7 pad bytes at p-7 are not all FORBIDDENBYTE (0xfd):
        at p-7: 0x00 *** OUCH
        at p-6: 0x00 *** OUCH
        at p-5: 0x00 *** OUCH
        at p-4: 0x00 *** OUCH
        at p-3: 0x00 *** OUCH
        at p-2: 0x00 *** OUCH
        at p-1: 0x00 *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=0x2d67c444d794c3a0 are [2021-01-11 16:14:11 +0100] [32113] [INFO] Booting worker with pid: 32113

(...)
---

You should report the issue to gunicorn: https://github.com/benoitc/gunicorn/issues