Pixelated border between ID map colours

[Sarnos]

Hey i got an issue with my ID map

https://imgur.com/a/Wzv5nDx

you can see yellow area has a heavy jagged shape and wonder how it is possible to avoid it, when setting the UV to 4kx4k it lessens slighty but is still very visible

I made the id map using blenders vertex paint and have not used a texture to creat the ID islands

[Jerc]

It looks like the ID map is using a lower resolution than the other maps. did you bake it in 4k?