iphone 11 videos do not show up in my icloud apple photos library on the M1 or 2012 iMac

Moving from iPhoto to Photos & iCloud: I have been using iPhoto and photo stream for many years to download photos monthly to my Mac, where they are backed up in several ways. My system library was huge ( as are several other iPhotos libraries) and I didn’t want to transfer all of the photos/videos into a monthly paid service, so I opted to create a new photos library, and in January 2021 transitioned to using iCloud to sync my photos starting with that new system photo library. Most has worked well, except that I now notice that my videos taken since January are not on the either mac. Neither are the Albums that I made on the iPhone, including Favorites. There may be other things missing also, but that needs more investigation. The shared albums do show up on the Macs.

Not quite as important. I also have iPad mini 4 which isn't synced at all with the iPhone photos, bc I have not yet turned on iCloud photos. When I eventually do, will that merge the content in iCloud or replace something?

All are using the the same iCloud account

2020 M1 MBA OS 11.2.3

2012 iMac OS 10.14.6

iPhone 11 Pro iOS 14.4.1

iPad Mini 4 14.4.2