Close to giving up on Nextcloud as an end user, not a developer.
NO SUPPORT - Queries go unansered.
Had a lot of success until recent atempt to upgrade, which failed. So I did a total re-install to a shared server. Can only connect via Firefox browser. Can no longer sync from Ubuntu 2004 nor Droid app.
Attempts to fix take so much time that I no longer save any - more time trying for solutions that worth the investment since I can not sync.
I was using 15. Could not upgrade - no upgrade “button” on the admin page. Maybe that was because I had upgraded to php 7.3 on the host. At least I was sycn-ing from all platforms and bragging to my Linux buddies about my cloud. So, I started from scratch, not being able to upgrade. As I understand you, I have to wait for php 7.4 to be available? That leaves me at the mercy of the hosting service and their time line. Am I missing anything, e.g., re-install with an earlier version of NC?
Well that’s not true, i am running multiple instances of Nextclouds on 7.3.19-1deb10u1 fine but without PLESK, webmin or any of these clicky-fancy admintools, just pure Debian Linux, Apache, MariaDB and PHP.
And regarding Nextcloud support: RainerNippes already said, that you can buy support not only at Nextcloud but elsewhere too. But of course nobody will offer his or her service on unknown blackboxes. Speaking for my self I only support managed nextclouds which I installed myself and have under my management. You should take this into your consideration before blaming the product itself.
I use cPanel to select version and upgrade PHP. I did that some time ago because NC notifications said PHP 7.3 is better! PHP 7.4 is not available via cPanel. I setup a new DB when doing the new install of NC but it likely has come content since I was able to establish users and login. I don’t know how to empty a DB and believe that the plesk command might be good on a local machine but not on a hosting service, on which, BTW, I do not have root privileges.