He weighed 60.5 during the Giro, which going by your post seems still needs to be said of that it was the first race after his crash, after a relapse in his rehab and a short prep without racedays, and he lost 90 seconds to Bernal after 15 days on Zoncolan. Only some seconds behind Vlasov who finished 3rd in Huy this week, and Carthy who both have a better track record on steep climbs. Considering the conditions, i don't think you should use his weight here as a point of reference. I think it's quite peculiar that the team now comes to the conclusion that his weight for a GT should be 63 instead of 60, based on the Giro where a lot of things went wrong, but him being too light didn't appear to be one of them.
During Burgos he weighed 61-62 going from interviews at the time. He won on Picon Blanco and finished 3rd on Lagunas de Neila, right after Landa and not too far behind Sosa who had been wheelsucking the entire climb and outpunched him and Landa in the final 500 meters. He finished ahead of a lot of other top rated climbers.
In Valencia he got dropped like a brick. In Tirreno he didn't even make it beyond the foot of the climb. I think it's fair to say his weight showed to be a big factor.
Him being more of a tempo climber and a TT'er has always been the case. However what we saw in Valencia and Tirreno was highly atypical. I think the strongest we've seen him is still the period in 2020, as well before the covid lockdown in San Juan and Algarve, as after the lockdown in Burgos and Poland. A good mix of TT, rouleur and climbing abilities.
Weighing 63 for a 1m71 guy would obviously be a big improvement over 66.5kg, which was downright ridiculous. But it is still far from what i would say is a big transformation, considering other GC guys of his height (and a lot taller even) weigh (a lot) less. So i would say that the ''improvement'' is still very subjective. Kuss, 1m80 / 61kg. Mas, 1m77 / 61kg. Bernal, 1m75 / 60 kg. I'm not saying he should aim to be 58kg, but 63 still seems like more than enough considering how few TT km there are in GT's currently. And i wouldn't call dropping from 66 to 63kg a complete transformation. More like the bare minimum.