Baldur's Gate 3

good for you mate

DA2 > Origins

Surprisingly that didn't happen to me, as i also replayed the game multiple times and every single time i promise i won't 100% it but then end up 100% it anyway because i can't just not engage with the content as its so good and offers different solutions.

I think every long game can have that, but in my opinion at least, Baldur's Gate 3 is one of the few long games where it felt fresh all the way through, maybe thats because the content is all killer and no filler, i can't recall any section in the world that i felt i was doing the same chores, every tiny spot on the world's map was filled with a unique encounter that spices up things and keeps the pacing adjusted.

When i compare it to other long games, i can't help but notice that its the least bloated one, the game that drags out the least.
For instance i remember Reddit Dead Redemption 2 first 4 chapters being so good, so cinematic and offering a plot with high stakes that keeps engaging you to know what happens next, then chapter 5 comes it completely breaks the pacing, with chapter 6 that drags way too much, but all is fine still, at that point i was happily playing the game, then the epilogue comes in and holy shit, thats a total drag, a total bloat for no reason, you are stuck FOR HOURS playing as John, doing daily chores that dont matter to the plot nor its engaging, one of those chore is like moving around stuff, or cleaning the stable of the horseshit or milking the cow, such riveting gameplay!
It drags for hours until we got a proper conclusion, all that happens in one of the most dry areas in the world.

Another acclaimed example is Elden Ring, after leaving the Capital Leyndell you reach out a snowy area, the mountaintops of the Giants, the game at this point offers nothing but more of the same, and it completely drags on and on until the finale which picks up the pace again with great boss fights, but the two snowy areas felt like complete filler, recycling bosses like Astel which was supposed to be one of the unique ones, recycling enemies while throwing combat balance out of the window.
I love Elden Ring but there is no denying that the back third of the game is a symptom to this long game problems you talk about.

Another acclaimed game i can offer is Witcher 3: Wild Hunt
The final act of the game after the Battle of Kaer Morhen has Geralt and Ciri going around to set up for the final battle and my god it drags too much as well offering nothing new in terms of gameplay nor enemies nor side quests.

The same thing happens with the new Zelda game, where it starts to be more of the same, but at least they kept introducing new mechanics, albeit they also keep recycling the same cutscenes and plot points.

I mean you get the gist, every long game has this, i just think this one in particular circles around this common issue very well, to the point that i personally didn't notice it.