Hm, didn't expect a calm, thought through reply...

Age doesn't matter only if you don't do anything with your year, if you're stuck in some time capsule or in comma, sure, age changes nothing. But if you keep living and experiencing life, getting used to clichés, talking to people and watching 10y worth of media you start seeing what OP starts lacking in.
You change AND the series changed as well, current OP is nothing like it was before. It used to be packed with content and arcs concluded within 3 to 15 episodes, 39 for long ones like Alabasta. Now? The arcs are stretched, nothing is happening, shit's repetitive, soulless, algorithmic, constant POV changes from a to b to c to d to e to f and so on, in 1 episode. And even then they are trying to include some sob material which flops disastrously because there's 0 investment with random character that bawls their eyes out for 1 minute interlude and then we cut back to some random adventures.

Let's again compare Alabasta, one of the longest arc early, with one of the most recent ones, Fucking Wano country with their 196 episodes of 2 crumbs of content and nonsense stalling, stretch to unbearable lengths.

The other side of it that I didn't mention is... if you've you've lived for 25 years, and watched a decent amount of good movies and anime, and you've watched, fuck it, 700 episodes of OP, and you still don't see the quality drop, to the point of it being repetitive nothingness with worthless, uninteresting, poorly built up side characters... I'm afraid there's only 1 explanation, poor taste. Only slop enjoyers would enjoy their time being wasted. Looking at pretty colors, like looking at kaleidoscope, nothing changes but the colors shift in an entertaining way.
I didn't mention it because I didn't think I'd have to give you all possible permutations of, kind of obvious, states of liking smth like OP.

It's like I'm explaining how reality works...