@jernej__s >The problem is that if you put NextCloud (or any other AGPLv3-licensed program) on the internet, you yourself have to provide the source code of your running instance to anybody who accesses it. How do you achieve that?
I don't see a problem with that myself, but you don't even need to provide the source code unless YOU modify it.

If you've made a modification to NextCloud, I don't see why you wouldn't be able to make a quick additional modification by slapping a link into the footer of the HTML pages.

A lot of AGPLv3 programs (like mastodon) have a modification notice as an automatic feature - it takes only a few minutes to paste a link to the source into the relevant section.