I have disconnected from the cloud on both my computer and iPhone to see if that will help
When you disable iCloud Photos and turn it on again, Photos will start over with the syncing. All files will be uploaded again to iCloud and it will take even longer before files from iCloud will download to your Mac.
Do it only, if you are sure that you have tried all other options.
What is the status bar showing in Photos on your Mac? You may want to check this support document:
About the status bar in Photos for macOS - Apple Support
Create the two smart albums described in this document and check for items, that are incompatible with iCloud.
If your Mac is stuck on uploading to iCloud, you may have older items in your Photos Library, that cannot be processed any longer after the upgrade to Catalina. Some video formats can no longer be used after you upgraded to Catalina. Also some older image formats.
Items that are unable to upload need to be removed from the Photos Library and converted to a different format. I had to remove older video clips and all PICT files and PDF files from my Photos Library, before it started syncing again.
Can you identify the items that do not appear i iCloud?
Also, devices with an older system version may have uploaded files to iCloud Photos, that a Mac with Catalina cannot download to Photos.
Keep only items in iCloud Photos that are compatible with the systems on all your devices.
This list might give you an idea which media formats should be avoided: About incompatible media in iMovie for macOS - Apple Support
