Created attachment 159431 [details] Screenshot Chrome has so-called "Chrome apps" which can be installed on some websites. Basically, they are websites in an independent window which can be started independent off chrome itself from Kickoff or Krunner. Unfortunately they lack the window decoration which I believe is normally provided by kwin/KDE. It has an independent window decoration which not only looks different. But also does not have all the features the kwin/KDE decoration has (e.g. I have configured my kwin/KDE decoration to have an item to always keep a window on top). I assume this problem also affects other chromium-based browsers like Opera, Edge and Chromium.
Apps are allowed to opt out of the KWin-provided SSD titlebar and draw their own CSD one, so I'm afraid this is a Chrome issue. I believe you can actually turn off the feature somewhere in Chrome and get an SSD titlebar back, though. Either way, not a KDE issue.
Hmm, if this can be done already. Couldn't this then be an issue for the KDE_plasma-Integration addon for Chrome? If so, could you reassign, instead of closing?
Switching from CSD mode to SSD mode is something that's out of scope for the browser integration feature. A lot of people like their browsers to use CSD mode; this is really a personal preference.