It's not a perfect comparison, but the last time Roglic did a GT whilst not 100% recovered from a crash in his previous GT was the 2022 Vuelta and he was clearly better there than at the 2025 Tour.
Catalunya doesn't matter to me because I'm ranking solely for GTs and after all the climbs were taken out of the Pradell stage, the hardest climb of the race would barely have been cat. 1 at the Tour. No proper mountains is a) better for Roglic than proper mountains and, more importantly, b) not representative whatsoever of GTs. And even if you want to go down that route, he was the worst I've seen him since his emergence as a GC rider on similar terrain in Algarve, so I don't think you can use one-week stage races as an argument against decline.
One-week stage races are informative of the strength of the rider, otherwise Ayuso wouldn't be in a top-20. And the upper-bound of performances is far more telling than the lower bound. Nibali being dogshit in stage races he didn't care about was never as informative as the level of his best performances. And keep in mind that it was the earliest stage race he has done since 2018, usually he starts his season with a serious WT stage race.
So Algarve and Catalunya showed that Rogla still has it and that he was at least as good in the spring this year as any other year. Much better than 2024, and no worse than 2019-2023. That indicates that age didn't materially affect him at that point and that his pre-season prep went well.
I also don't think 2022 and 2025 is a good comparison, but here too I think 2025 was better. Ventoux >> Sierra de La Pandera, and nothing else he did that Vuelta was on a high level. Had he not ridden for Lipowitz, but ridden seriously for as good a GC spot as possible, he'd also not have thrown it away in the Alps but easily finished top-5.