He's slightly better than the 2023 Vuelta IMO, and he just happened to not be on a great day on the most important MTF of the race.
In 2023 he had a really poor stretch where he was very lucky the damage was minimal, but it included struggling on Xorret de Catí and getting deleted in the sprint after, getting easily gapped on Caravaca de la Cruz where he didn't wind up losing seconds because of the wonky finish line timings, and it included a really poor time trial where he barely put time into Kuss.
Then on the Tourmalet he attacks first and he takes like 30-40s with a tailwind while they're playing tactical games behind. Bejes was 100% down to tactical games behind as well, and on the Angliru they were only 30s slower than this year despite way suboptimal pacing, so I doubt very much even Vingegaard could have easily gone much faster.