Whether I launch Pages v14.4 on Sequoia v15.5 with a local 200 page document, or a one page document with text and equations from iCloud Drive, its CPU utilization with Pages at idle is less than 1%. This would naturally increase if I was actually working on a document performing a spell check, playijng an embedded video, or removing an image background. I don't see what you observe in Activity Monitor, and what you show is not what I consider high CPU utilization for a user application on a UNIX operating system.
Personally, I don't waste a minute looking at Activity Monitor. In most cases, including yours, there is nothing you can do other than close that Pages document(s), quit Pages, and potentially reboot. Pages is unlikely to be bug free, yet there is nothing in your post that suggests that this is a bug.