FWIW, my ad blocking takes place network wide via AdGuard DNS. Switching to a conventional DNS server makes the game not crash (iOS 17.3.1). Point being, I don’t think the ad blocker is the root cause as much as the ad blocking.
FWIW, a commenter mentioned in MCPE-179540 that the problem went away for them when they allowed vortex.data.microsoft.com at their adblocker.
Confirmed fixed in 1.20.72. Thank you!