What problem does this address?

The current notes implementation may not scale well when there are many (hundreds or thousands) notes (or comment replies) on a post.

The comment REST API endpoint only returns 100 records at a time so fetching many will require multiple requests - my expectation is the current UI will only display comments when all comments have loaded.

Note that for the initial display we only show the top level comments (plus a message about the number of replies). Clicking a comment threat shows the replies.

What is your proposed solution?

• Only load top level comments in the initial request
• In the background load all of the (remaining) data
• Ensure data fetching properly paginates thru >100 records
• Possibly/future: display comment placeholders until first request request completes to avoid layout shift (we already know which blocks have comments). this applies more once we have comments positioned next to their related block in popovers.

related (see especially recent discussion): #10169