Hey there Bongjuice420,
Thanks for reaching out to the Apple Support Communities.
To get started, how much storage do you currently have available in iCloud? We ask because if you go over your iCloud storage limit, you may not be able to sync all the photos on your device with iCloud.
For more details and help with troubleshooting issues with iCloud Photos not working as expected, check out this link here: Get help with iCloud Photos - Apple Support
What happens when I go over my iCloud storage limit?
If you exceed your iCloud storage limit, photos and videos won't upload to iCloud and your library won’t stay up to date across your devices. To continue using iCloud Photos, upgrade your storage plan or reduce the amount of storage that you're using.
Reduce the storage for iCloud Photos by deleting photos and videos that you don't want to keep from your iOS and iPadOS devices or on iCloud.com. Your device will immediately remove any photos and videos that you delete and they won't be available for recovery in your Recently Deleted album.
If you're out of storage, your devices won't back up to iCloud, and new photos, videos, documents, and your information won't stay up to date.
Keep us updated now what you find after going through the resource above, and we'll continue from there.
Have a great day!