Laptop sometimes not going to sleep

I'm on OpenCore Matebook X Pro Monterey, but this also happened on Big Sur if I recall correctly. Sometimes, quite often actually, when I close the laptop lid for some time and then open it back up, laptop screen is indeed dark and I have to wake it up, but the battery has drained substantially, and if I check battery usage, it shows as if the laptop was being used, all this time. I don't know whats causing this, so is there a way for me to check what is preventing sleep?

Also when power on the laptop, some glitching occurs sometimes while turning on, is this normal?

Thanks