Update your macOS to v15.4.1 if you have not already. That shouldn't make a difference to Pages v14.4 but there are some important bug and security fixes in that update.
If you have installed any anti-virus, or any so-called "Mac cleaning" tool. Remove them per vendors instructions and reboot the Mac. I don't install this junk and my Pages v14.4 on macOS Sequoia v15.4.1 does not misbehave.
Press and hold the shift key while launching Pages. That will force it to not use its last saved execution state (crash or hang) and it may break the cycle you are in. Does the application immediately crash upon launch, or is it a specific document that you are attempting to open when it crashes?