If I use Google Chrome with the "Use system title bar and borders" option turned off in the Chrome settings and maximize the window then the window controls are missing. I didn't have this issue with Netrunner 17 when I tried it so I'm assuming this isn't a bug with Chrome itself.
What Window Decoration do you use? Does this happen with any of the other window decorations too?
I'm using the Maui default window decoration. It does happen with the other window decorations as well.
With the "Use system title bar and borders" disabled, it doesn't matter what window decorations are used in plasma, Chrome and/or chromium is going to use it's own internal widget set. Maybe there is a compositor settings that is different from you previous NR17 install?
I tried matching the compositor settings to that I have on my Netrunner 17 installation to no avail. I also tried disabling the compositor entirely and even after a reboot still no joy.
Please stick to the system title bar borders for now. It seems to be an issue with kwin and chrome/chromium upstream, also happening on neon.