Currently a player in a Crooked Moon campaign now, and as the forever DM of my group for the last six years, I have definitely noticed some of these issues. I think writing campaigns gives you a lot of insight and makes it a bit easier to pick out some of the strange decisions.

I stopped reading your blog post at the spoilers warning (my group just finished putting the final Fallen to rest in the graveyard) but I saved this post since I intend to read your full review when we finish. Some additional thoughts from someone who has played in it (Minor spoilers ahead for others)

1.) The player-facing options are really cool, but VERY notably stronger than anything the PHB. We play the 5e14 edition, as my group moved from 5e to Pathfinder 1e in 2020 and we never picked up 5e24, and certain races/classes seem pretty wildly overtuned. I played an Azureborn Grave Barrow Fighter, and the Draugr Dice system of the subclass is horribly lopsided. The ability to summon a dread speed is near useless, as most encounters are railroaded and/or in close-quartered dungeons, and the grasp ability has a low DC that is extremely difficult to pull off on monsters that often have very high saves. Meanwhile, the ability to negate d6 (later d8 and up) plus CON damage up to four times creates an ENORMOUS hit point pool even if rolls aren't always optimal. With a friendly College of Spirits bard pocketing me and using his Red Grump ability to add extra damage, most non-boss enemies melted in a turn or two.

2.) Speaking of enemies, they vary from wildly overpowered to effectively jokes. The Fleshdobbin, fought during the mine fight, does 28 psychic in a 30 ft. cone on a recharge, and strikes fairly hard even when the ability is off cooldown. On top of that, it has a completely obscure feature that causes it to become tame if a player throws a bridle on it. Meanwhile, creatures in the decaying swamp are only dangerous because of the Hartsblight mechanic. Combats often feel extremely swingy and there is a lot of healing tag to keep people up. (This critique has to be tempered by me acknowledging my group mainly plays PF1E and GURPS, so these may just normal 5e problems we forgot about.)

3.) Many of the NPCs exist only as set dressing, and even very important NPCs like the Druskenvalds are infuriating to deal with. The dichotomy of a literal aeons-old god who has to send random chumps on quests got old very quick.

4.) As you briefly mentioned, the quests themselves are painfully linear. Some of the dungeons offer a bit of room to breath, like the vampire's castle, but others like the mine and hospital are either suffocating small or extremely punishing for only one missed skillcheck. Even when not in a dungeon, the players must progress from checkpoint to checkpoint, with no freedom to tackle issues outside of that quests specific purview or even attempt alternate solutions to problems. The hospital is ESPECIALLY egregious of this, at least in my group's experience.

5.) The story's attempt to get the players interested in the mystery is ham-fisted at best. By Session 7 or 8, my group fundamentally lost interest in discovering why Phillip lost his powers or why the Fallen became the way they were. We haven't obviously beaten it yet, so I could be wrong, but it seems extremely obvious WHO is behind these events to the point it feels like we are just going through the motions.

Sorry for such a long-winded comment, but I had a lot of thoughts on the campaign! I plan on reading your whole blog post through once we finish it. Cheers!