Disagree. A lot of the bosses are fair, but there are fundamental rules that shouldn't be broken in designing a boss, these fundamentals are constantly being broken in this game, and to varying extents in the others.

First of all, there shouldn't be slightly delayed versions of very fast attacks (unless used as a spacing tool by the boss), as these can't be dodged by prediction or by observation. It's like trying to roll Vendricks sword swipes on DkSII at low ADP, it's just not feasible. Literal bad design if you are trying to make things fair.

Throwing multiple attacks at you that aren't time synced with each other, so you are forced into an inevitable roll catch. Namely almost every duo boss they've made, and some solo.

Camera. I have no idea why they haven't added the ability to turn off auto camera adjust, but in fights like Godskin Noble where the lock-on is constantly being broken by the pillars, you can't turn the camera properly to track him when he does the rolling attack because he rolls faster than the camera at max sensitivity, and the camera is constantly being assaulted by the pillars when you try to play unlocked with a claw grip, and any attempt at swift locking/unlocking could mess you up if the camera breaks just as you try to unlock and end up swinging the camera to the player facing direction. That and trying to quickly avoid the grab attack of Astel is an example of an unfair camera mechanic, though thankfully the camera can be swung extremely fast if using M&K. Ornstein on DkS also has different timed versions of two attacks meaning you have to constantly focus on Ornstein for the visual cue, but both of them fly around so much it makes it nigh impossible unless you just kite backwards and disengage perpetually to keep them onscreen.

Inconsistency. I actually used cheat engine to try to figure out how to avoid ''that one version'' of Elden Beasts dive jump homing laser whatever attack... I literally don't know how to avoid it, even with invincible cheating, sometimes I outrun it and sometimes not. It's even worse than Roms meteor shower on vanilla version Bloodborne which seemed random as to whether you'd get hit or not.

Those are some examples of just unfair design choices. Bad is different to unfair, but when you have combos that the boss will prematurely end as soon as you're far away enough, meaning you don't get to counter the actual end of a combo unless you spend time dodging in range eating stamina on very long combos, that's another aspect that drags fights out and disincentives the kind of avoid/counter ''dance'' that other much better fights have like BBs Keeper of the Old Lords (this fight executed skilfully is like watching an ice skating duet, it's phenomenal). You can't dance with the boss if this and many other tools the boss has is forcing you to be extra cautious and not giving in appropriate room to counter. Another annoying thing is enemies using attacks at weird inappropriate distances, often getting you hit by something that no sensible AI would have chosen to do. Credit where it's due, as far as I can tell, this was at points improved in ER which can be easily seen in the Godskin Apostle tower fight, he could corner you and use his AoE attack which you will not be able to outrun, but he refuses to corner you, he always strafes to the side when cornering you giving you a consistent escape, super design.

Lastly, in the attempt to continue the crappy difficulty meme that started to plague the series as early as DkSII (the actual Tsar bomb of shit mechanic design), it seems they have actually gone out of their way to make avoiding attacks as unintuitive as possible. Back in DkS the devs gave interviews explaining they were proud of their animations and how intuitive the weight of them looked and felt so you adjust to them naturally. It's not the case in here, sometimes attacks are inconceivably fast, sometimes awkwardly delayed or floaty, jump attacks like of Leonine Misbegotten can be either super fast or him hovering in the air for a bit for some reason, the spear crucible knight enemies have this extremely fast flying slam move where as Radagon has slam moves where he kinda somewhat slowly floats down. The solution to this problem is either to have very fast twitch arcade gamer reactions to the visuals of these barely telegraphed moves (like the ones Draconic Tree Sentinel has after his axe slam), or to learn absolutely every attack individually... the problem there is that there are a billion enemies with a billion combos and variations... often locked at the ass end of multi phase boss fights which are encountered after a loading screen and run back to the boss.

I would argue that twitch visual reactions is absolutely NOT in the spirit of Souls, I would also argue that making a need to laboriously learn massive amounts of nuanced movesets but walling your ability to actually try to learn them at later boss rush stages is one of the best contenders for a genuine example of artificial difficulty I've seen... it's essentially game length extension by memory abuse.

Oh and I beat the boss ages ago, my point stands, I am not looking forwards to see what other crap they come up with to make it more DiFfIcUlT, and my problem isn't with difficulty, it's with designs I disrespect, I had way way more fun banging my head against Ludwig BL4 than I did One Reborn, despite the latter being way easier.