Remnote is a note taking app that has a built in PDF reader, when you highlight something in the PDF it gets copied to the clipboard so you can paste it in your notes. However, if Popclip is running then the highlight does not get copied to the clipboard. If you close Popclip or add the browser you are using (I am using Arc) to Popclip’s exclusions then it also works fine.
I tried with Chrome and the same problem: the highlight doesn’t get copied to the clipboard if Popclip is running.
I have also informed Remnote about this.