Unfortunately for some apps it is not possible to activate just a specific window for pasting. That's why they will bring up all other windows belonging to them (because BTT needs to activate the app to make sure the correct window & app receives the paste event)
Thanks for your explanation. This behavior is really frustrating, since I always have multiple windows open in parallel and when I want to copy & paste between browser and ppt it's really annoying.
Nevermind, I guess you have implemented it based on your long lasting experience with the BTT Clipboard Manager. Maccy does not seem to have this behavior - but maybe Maccy therefore somehow fails to paste correctly - I don't know.
There is another way to bring only a specific window to front, but it had glitches on some macOS versions - I'm not quite sure how it behaves on current. I can add an option for the clipboard manager to use that, maybe it works well nowadays.