Why does the MCU hate Bucky?

This guy used to be able to match Steve Rogers in a one on one fight in CATWS. Was dealing with Black Widow and Falcon like they were pesky gnats.

Then in Civil War he gets easily dominated by Spiderman who himself was defeated by Captain America later on.

In Infinity War he can't even keep up with the running pace set by Black Panther and Captain America.

Now in TFATWS he regularly struggles with random untrained thugs just because they were injected with the ss serum and was completely outmatched by a 2nd rate Captain America.

Now, we can theorize that Walker is just a far better fighter than Steve Rogers seeing as he's competely able to dominate an opponent that Steve struggled with, but the fact that Falcon puts up a better fight against Walker than Bucky seems to indicate that they simply just nerfed Bucky that badly.

The question is why? I don't think any other MCU character has been downgraded as much as the Winter Soldier, not even Hulk. So why does the MCU hate Bucky so much?