Albeit infamous among fans, KayCyy was a vital figure in the album's creation process. He did a lot of writing work (lot of it wasn't used) and helped crafting some of the highlights of the album.

1. Hurricane:

He did the bridge in August 2020. He talks about it in this interview:

complex.com/music/kaycyy-interview-flew-by-you

There was so much going on in Wyoming. ’Ye was doing whatever he was doing with the fashion stuff, but it’s all happening in the same area. So Baby and I were sitting there, listening to the album and trying to figure out what song he should get on. I came in and told him, “I think you should get on ‘Hurricane.’ It’s going to be one of the biggest songs, because it’s the most anticipated one.” I’m like, “If you get on it, it’ll be wild.” So he did that. He gave an amazing verse, and it stayed on topic of what we were aiming for—like gospel music, and not swearing and doing too much of that. He did amazing, and I’m like, “Alright, cool. This s*** sounds fire. How can I get on the song?” So I figured out a way to just add my vocals on it. Like an outro bridge. And then ’Ye actually ended up f***ing with it. It was crazy.

The song was changed for 2021, Kanye removed his old verse and attached verse from a song called 'City Of Lost Angels' but KayCyy and Lil Baby's part remained the same. He got the writing credits for it as Weeknd used it and as @rhymingrhino pointed out, has background vocals on the bridge still.
Can't post it as UMG copystrikes any video containing it.

2. 24

He made the very first version of the song in remembrance of Kobe, 3 days after he passed. Kanye allegedly cried after hearing it. It was called 24 Hours then.

Snippets of various versions of the track featuring KayCyy:

He has background vocals on the released version.

3. Praise God

He made the very 1st version of the track and was the ref for Travis. We have the mumble demo:

Track sampled a song called Dream of You by Mariya Takeuchi back then.

He later filled in the vocals with proper vocals and was the feat along with Travis in July 2020.

4. In God's Country

Track featuring Justin Bieber and Common, didn't make it to final album. KayCyy did the ref for Justin Bieber.

5. Fighting Fires:

Another track he made the very first version of, in November 2019.

6. Wash Us In The Blood:

Filling in Ye's lyrics from the 1st mumble demo Ye made. His ref doesn't seems to have been used a lot for final version.

7. God's Test:

Song snippet that was in the YZY TV Documentary and it was on a leaked Jan 2021 Donda Tracklist

8. Ok Ok

A version featuring him, Fivio Foreign and Lil Yachty was played at the Atlanta Listening Party 2 rehearsals, a Low Quality snippet had surfaced:

9. Random refs he did during the era allegedly for Ye:

10. According to leakers he did some work on some versions of following tracks : Lord I Need You, Off The Grid, No Child Left Behind.
We have no snippets of these.
KayCyy also implied he worked on Skurrrurrr, a song from July 2020 Donda tracklist.

11. Keep My Spirit Alive

The contribution that made it to the album. Version featuring his hook released today as Pt. 2 on the deluxe, after infamously being removed off of the album.

A version KayCyy plays at his concerts with an extended verse of his and longer Kanye verse, OG Beat and no Griselda.

What are your thoughts on his contributions.

Anything I missed?

High quality thread

thank you for this, i have a newfound appreciation for him now

memes aside very talented artist, really did his thing

we thank KC for all this and then some.

we really need In God's country finished this s*** sounded unreal

KC sounds angelic on it

op is kaycyy pluto

He still has background vocals on the hurricane bridge

f*** u kaycycy plu\to

on 24 too

actually theyre more like foreground vocals on 24

I’m surprised no one called them mid-ground vocals yet with all the KC haters after he “leaked” LOTP lol

I will always follllow your leaddddd

24 is kind of a mess, don't know if he's supposed to be there. There is completely random vocals present in the stems of the song:

vocaroo.com/1oHFojoRaWGn

Lyrics seem to be 'Let them onto onto you, we gonna be ok'. Timeline would suggest it being Lancey Foux but doesn't really sounds like him.

gods test monday

kaycyy is def supposed to be on it but idk about that or whos singing that

They kaycy vocals on 24 are like the little humming before a choir part in the middle of the song

W thread

Shoutout kc

u all need to check him out on soundcloud he's got some gems

Thank god Bieber didn’t make it