heavy on server

Expected behaviour

stress nextcloud server similar to nextcloud webUI or android nextcloud app, or webdav cases

Actual behaviour

caused heavy mysql usage on nextcloud server (ubuntu nextcloud snap) - often mysql process takes 50-150% cpu/core lasting hour and more, even after killing nextcloud ios app. stressed server always result in nextcloud ios app to timeout even on most simple file access, and cause timeout problem for android nextcloud app

Only notices the problem recently, with app timeouts and super heavy mysql process on nextcloud server

Steps to reproduce

install nextcloud ios app, setup account, no change to settings

Reasoning or why should it be changed/implemented?

nextcloud app never update file changes

iOS version

tested on both iPadOS 13.3.1 and iOS 12.4.5, same result

App version

2.52.9

Server configuration

nextcloud server from Ubuntu snap store, configured with sftp external storage on local account

Operating system:
Ubuntu 19.10

Web server:
Apache, part of Ubuntu snap packaged nextcloud server

Database:
MySQL, part of Ubuntu snap packaged nextcloud server

PHP version:
part of Ubuntu snap packaged nextcloud server

Nextcloud version: (see Nextcloud admin page)
17.0.3

Start by reproducing the issue with iOS app 2.52.9 against Nextcloud 17.0.3 from the Ubuntu snap, using the reported MySQL setup and SFTP external storage. Observe whether file-change checks produce sustained MySQL CPU usage and timeouts; done means file updates work without prolonged server load or app access timeouts.