I have maintained a Nextcloud server for a small business for the last 6 years.
I agree when I started using it early 2020 that the ui felt less modern, but after some updates down the road up until now it looks completely like it is from this era. Am I missing something?
However, I never complained about the UI neither then nor now.
NextCloud generally appears to use their own design system everywhere, Android apps are also not in Material or on iOS (iirc) in Cupertino. It makes for a subpar experience in general but is consistent.
This is the decade where every company bought into flat design, monochrome, chonky whitespace, extremely radiused corners everywhere. Pulling up my instance, Nextcloud apes that to a tee. You'd be hard-pressed to find any "modern" UI trend that they haven't shoe-horned into their design somehow.
The _did_ completely redo their UI a few years back, and for the worse in my opinion. The Calendar in particular is far less usable and (and much more buggy) than it was around the time it was forked from OwnCloud.
That is not a compelling reason to overhaul a UI (which is something that should rarely, if ever, be done). If it works and is pleasant to use, what it looks like is of no consequence.
I have maintained a Nextcloud server for a small business for the last 6 years. I agree when I started using it early 2020 that the ui felt less modern, but after some updates down the road up until now it looks completely like it is from this era. Am I missing something? However, I never complained about the UI neither then nor now.