After trying everything available on any thread across forums, I finally got WA on my iPhone 13 working fine!!! This has been working for me for a month now!! I was waiting to see how long it would take, and so far (touchwood!) all's been well.
- I added a new SIM/phone number to my phone
- Took the iCloud backup for existing WA and deleted the app after that
- Reinstalled the app, this time started afresh with the new phone number.
- Deleted the app again
- Reinstalled the app, restored my old phone number
- Voila! It stopped crashing.
Now, for details, my new number did not have any chat backup to screw up from. So, it kind of got disconnected from iCloud. I pray hard enough every day that it continues to work flawlessly as it does finally, because I know how much pain it is. I had done multiple loops of going through WA support (which was useless), writing to Apple, following people of forum, basically been in a mess, regretting the upgrade.
So far, so good. Worth a try.