Looks like someone took the opportunity to snaffle a bit of cake on the quiet...

Pedant point - Merlin, not eBird!

Yeah, looks like an error in regional boundaries. There are a few in other areas of UK also. Best write up an email and send to eBird help. Will take a while to sort though (they get constant hassle about the contested border between India & Pakistan for example!)

If this an error, can you screenshot where your list is 149?

If you know the dates and locations, #eBird Explore on the web is still pretty handy to find the checklists and maybe the individuals. Sometimes they put contact details in their bios.

I think it is too much to ask. So many issues with privacy, and safety, I guess. A lot of backend effort to make it flexible for everyone.

This uses BirdNet engine yes? Would be interested to see how this performs for UK birds Steve.

There are several taxa like "finch sp.", "pipit sp.", even a "passerine sp.".

You could use the most appropriate one of those for flocks you couldn't identify to species level?