Eventually we found out that was because of a knee injury though
I'd take that with a pinch of salt tbh. The manager blames it on him crashing into the Visma car pre race on the 18th stage, someone else said it flared up on the 17th stage. He was already looking like he hated being there sometime earlier.
Pogacar's own words in the 3rd week were along the lines of "I can't wait for this to be over so I can go and do something fun with my life"
I think Visma - chasing an idea that they could tire him out and get something in the third week - made him race far more conservatively than he might have liked (pressure from his team management as well?) and he hated it.
I expect to see Visma repeat this strat again, harrying and harassing from early on and making it hard and irritating. While I doubt Seixas is in any way a serious contender this season it's likely he'll be involved, especially early on.
EDIT: I don't expect either Pog or Vingegaard to be anything but completely fresh at the start of the Tour. It'll be the three weeks that counts, not what they've raced earlier in the season.