This is all way too nitpicky, so take it with some salt, but some lingering questions...
Agnes Jurati is getting away with murder. Why?
Seven and Raffi spoke enough lines to one another at some point to land in a relationship in the final moments? What?
What did Elnor really do this season to warrant his inclusion? What did Seven do that Hugh couldn't have done? His death seems all the more unnecessary. This episode ends with the borg cube and all those ex b's not even being mentioned. Why would Seven and Elnor be on Rios's ship with Picard at all? Wasn't their whole thing staying and dealing with the ex borg's?
This alien race they just contacted, the beacon opened a portal. Message sent. Why didn't this galaxy spanning synth race just reopen the portal and come through on their own? They're this advanced, you'd think them capable of it.
Why did Commodore Oh not fire on the planet? Why did she back down when her whole mission is to save biological life as we know it? Why didn't she out that reason to Starfleet in the stand off? Why didn't she fire on the ships and go down in a blaze of fire trying to destroy the beacon and the synths from contacting this race in the future? In her mind she's saving all biological life. How could she back down given what was shown?
The beacon was made once. Any of the synths can go make it again. Are they just left on their own now, free to one day open a portal to a race that will annihilate all life as we know it? Aren't things dire right now? That race was contacted and are on their way, no? One day? The scope of this threat really didn't need to be this massive and unwieldy.
Also, why was Data trapped in that box? I get Spiner didn't want to come back and play Data. Makes sense as to why he was killed off. But in universe, shouldn't he have been placed in another synth body on that planet some years ago? If not in a new body, there's countless starships out there. Turn his consciousness into a hologram and give him a mobile emitter. Or have him in a holodeck on a starship doing work from there. Endless possibilities, making a new synth body one of the more obvious ways to go. They have B4's body. It shouldn't have been that hard to bring Data back when there's all these other synths on the planet.
Did they ever mention what became of Sutra? Did Soong just knock her out or did he murder her? Won't she have to be imprisoned forever if he didn't murder her?
My biggest nitpick with the whole episode was when all those carbon copy Starfleet ships warped in. Such air out of the sails. There is so much diversity of design in Starfleet, and the cgi just seemed off. If money was an issue, why not just say there's a fleet of 28 Romulan ships and send in a dozen Starfleet ships, instead of 100s to the point of it looking how it looked. Too many ships.
I thought this was a pretty compelling and beautiful episode overall. So many great and poignant moments. But I don't know why no one was asking some of these questions when this show was getting made.The way things ended it looked like they were staying on Rios's ship? Doing?