For Mac OS sometimes the "command" + "backtick" doesn't cycle through all of the windows of an application
Coming from Windows and Linux, the Cmd+Tab and Cmd+Backtick of Macos feels half baked and annoying to me.
Luckily there's an amazing Open source alternative Alt-Tab!!
Here's the link: https://alt-tab-macos.netlify.app/
I've installed this and it's really awesome. It has options for both all apps alt-tabbing as well as apps of one single app with Alt+Backtick.
Also Alt+backtick works even if all windows of one app are not in same desktop.