Crash after saving scan of high page count document

Expected behaviour

No crash.

Actual behaviour

When scanning a document in the iOS app, normally after tapping 'save' it pauses for a moment, and puts it in the upload queue.

Instead, I try and scan a larger document (usually ~20 pages), it will consistently crash and lose the document.

Note that this has persisted for a while across the last few app and iOS versions, I just haven't written an issue report until now.

Steps to reproduce

Scan a document using the scan to PDF options. Scan about 20 pages. Try to save.

iOS version

14.2, but as mentioned above it also occurred on earlier versions.

App version

3.0.15.2 @ 2020, but as mentioned above it also occurred on earlier versions.

Server configuration

Container:
dockerhub image benyanke/nextcloud

Database:
MySQL

PHP version:
All recent versions

Nextcloud version: (see Nextcloud admin page)
All recent versions up to my current install of 19.0.3

Start by reproducing the crash in the iOS app using the reported setup: scan about 20 pages with scan-to-PDF and tap Save. Trace the save and upload-queue path from the failure, then verify that large documents save without crashing or being lost.