MBP and MBA running 15.3 -- Safari not syncing -- which MacBook has "priority / seniority" so to speak?

I can create a note in the Notes app on the MBA and it shows up on the MBP and vice versa. But I can't create a folder and put bookmarks in the folder in the *Favorites* of Safari on the MBA and have it show up on the MBP, even though I have Safari to be synced via iCloud. I have tried toggling Sync to iCloud till I'm blue in the face. Both are running macOS 15.3; MBA is M3 and MBP is M4, though the hardware shouldn't matter. When I make a change on the MBA it does show up in Safari on iPhone and iPad. Is this a known issue with MacBooks or am I just unlucky? Is there a hierarchy such that one MacBook is considered the *authority* and other devices / MacBooks fall in line behind it? TYIA.