I finished the game, took me around 19 hrs on Hardcore (I tried to explore every nook and cranny, managed to find every treasure in the game, but missed a bunch of breakable Salazar figurines).
Things that were cut in the village chapters:
- cable car segment (you can see cable car in the distance, so maybe it got cut for pacing reasons);
- rolling boulder segment (replaced with an explosive avalanche QTE);
- split path between el gigante and chainsaw ladies (now there's only one path, the one with chainsaw ladies);
- no rusty truck sequence;
Things that were cut in the castle chapters:
- Salazar's moving statue was turned into a tiny collectible thingy. There's a similar Salazar statue that you encounter shortly before the final boss of the castle, but it doesn't move except for its head
- clocktower segment where you must locate and shoot pieces of wood that stuck in cogs;
- Garrador cage fight (the cage is still in the game, but it only shows up in a cutscene and used to split Leon and Ashley);
- sewers (novistadors were relocated to a very short underground section before Verdugo);
- lava room with fire-breathing dragon statues;
- spiked ceiling trap and tunnel-boring machine trap;
- cultist manning a turret (replaced by an armored el gigante throwing rocks at you in the castle battlements);
- desert-themed catacombs under the castle (now there are only two short minecart segments, and a novistador hive);
Things that were cut in the island segment:
- no laser hallway (the throne room is still in the game, it just got relocated to the castle);
- no Ashley driving a bulldozer (bulldozer and wrecking ball segments were merged together into a separate section where you must defend Ashley while she's operating a machine);
- no crane game in the waste treatment plant;
- no suspended cages segment and no U3 bossfight. However, the game has a very notable memo item that describes U-3. Why would devs even put it into the game if not to tease U3 for the upcoming Ada DLC?
Mechanical downgrades:
- sluggish and overly realistic movement system;
- indestructible wooden doors;
- incendiary grenades (the game has fire/burning effects, so grenade was likely cut for redundancy reasons);
- Ashley's AI (you can no longer order her to wait in one place, I found certain sections of the game to be way harder because of that as she kept getting herself killed);
- Ashley's health (her AI is dumber, so my guess is that devs removed her healthbar after playtesters complained that she kept getting damaged);
- minecart section is way worse - the ride itself is very short, you can't move while in the cart, all enemies die in one hit except for a chainsaw freak, and you also have infinite ammo (because the devs had to prevent players from running out of ammo).
I'm also pretty sure that "Assignment Ada" is cut too, and unlike "Mercenaries" and "Separate Ways", it's not going to be patched-in at a later date.