Client login failed when uploading, serious issue

I have 3 Apple devices all running the latest version of iOS 13 (upgraded about 2-3 days ago from iOS 12, the nextcloud iOS client worked fine). This issue started after upgrading to Nextcloud 16.0.5 from 16.0.4 yesterday (there were no config etc changes other than the version number).

When I upload using the iOS client on any of the devices, the iOS client suddenly stops the upload mid way and starts asking me to login again. The upload also seems to go very slow (even though I'm on the local network as the nextcloud server).

From the logs, I see multiple messages like this from the 3 devices (I sanitized the some of the data in the log below):

{"reqId":"xxxxxxxxx","level":2,"time":"2019-09-27T14:07:21+00:00","remoteAddr":"192.168.1.xxx","user":"--","app":"core","method":"PROPFIND","url":"/remote.php/webdav/data/2019/09","message":"Login failed: 'xxxx' (Remote IP: '192.168.1.xxx')","userAgent":"Mozilla/5.0 (iOS) Nextcloud-iOS/2.24.1","version":"16.0.5.1"}

All of the devices have the latest nextcloud iOS client. I even uninstalled and reinstalled to no avail. As soon as I reinstall, login, and start upload, midway it prompts me to login again with the log saying "login failed".

Start by reproducing an upload with the Nextcloud iOS client 2.24.1 against Nextcloud 16.0.5 and compare the client behavior with the provided PROPFIND login-failure logs. No source file or test is named; done means identifying and fixing the cause of the mid-upload reauthentication and adding verification that uploads complete without prompting for login.