We virtually know nothing about Vadic, yet she seems to know about everyone. She knew Picard was synthetic. She knew Captain Shawn's psychological history. I doubt that kind of information is common knowledge because everyone was at a loss for any quickwit replies.
That portal weapon would be a lot more useful if it did not work only short range and in times of battle. If the founders want revenge, it's plausible they would want an on-demand portal to transport themselves from the gamma quadrant. The portal weapon was stolen from the Daystrom Institute, right? What else could be stolen that the portal weapon was a distraction? The stolen portal weapon is fairly new, yet shape-shifting impostors or the like are probably from before Bajor's prophets' wormhole was destroyed. The founders did say they implanted little new members of their species throughout the galaxy only for them to come home to the gamma quadrant later. They might have formed a secret organization for their revenge. This implies The Shrike works for the changelings or Vadic is one. It doesn't explain why Vadic would need Jack Crusher to fall in that gravity hole, since she clearly doesn't want him dead,. How exactly were they chased into that specific nebula that Vadic needed to send Jack into the middle of? Is there something Beverly and Jack know that they're not telling the rest of the crew?
Picard's strategizing capabilities were fine until he told Riker that they should hide, who nicely told Shaw the same. He did not assess Titan's capabilities, did not try maneuvering while shooting, did not specify where to target, did not look for vulnerabilities of the Shrike. Too much away from from Starfleet that he did not know decommissioned starbases, and now Riker throws him out of the bridge for essentially killing them all. How much of it is dementia, because last season everything was OK? How much of it is degradation of his synthetic self? I think they made it clear last season that he was a synth but not immortal.