I don't know how we can make this claim? Do we have objective data? I think logically - logically Pog is still only 24 years old. I know riders mature at different rates for many variables, but unless Pogacar had interrupted prep, he should have a higher physiological level at 24 than he did at 23. So, in spring of this season he logically had to be in better shape - and his results in spring seemed to confirm this. Now, after his crash I am not so certain.
In a way I tend to agree with @Andy schleck that his climbing on longer ascents seems to have plateaued since 2020. OTOH he's progressed significantly in one-day races since then.