Wide, white URL bar in Nextcloud as Chrome web app

I use my private Nextcloud (current version) with a Chrome web app as frontend on a KDE desktop under Linux. When I click on the desktop icon, the web app opens with the linked start page and everything works as expected. As soon as I click on another module in the menu bar (e.g. Files), an additional fat white bar appears at the top showing the URL, which wastes space unnecessarily and spoils the look. How can I prevent this?

I now suspect that the reason is that the URL changes depending on the module called up and Chrome displays the address bar in the web app as a result. I’m just wondering why other web apps don’t show this behavior and I’m wondering if there’s somewhere to set it. I can’t find anything to do this.

Many thanks in advance.