My last company was the first place I've worked that moved offices while I was there, and we definitely experienced a 'weird feeling' and we lost a bunch of people. Everything just felt off after the move, even though things went smoothly, and our new space was objectively much nicer (upgraded from thoroughly class C space to a nice class A building).
I was trying to stick it out and wait for the culture and mood (which had been fantastic beforehand) to get back in the groove, but our best people started to leave one by one, then one of the founders of my current company reached out to me personally, and it was too hard to pass up.
The key element in moving offices is buy-in. It affects everybody. If you treat your employees like they're part of the furniture during the planning phase then you're going to have exactly the effect you describe. Not saying that was the case but I would not be surprised if it was.
I was trying to stick it out and wait for the culture and mood (which had been fantastic beforehand) to get back in the groove, but our best people started to leave one by one, then one of the founders of my current company reached out to me personally, and it was too hard to pass up.