I've been following along with Imphenzias video on Low Poly modelling and when i get the part of picking colour in the UV editor the colours are hazy and cloudy. like steam on a mirror if that makes sense? i'm very very new to Blender so i haven't probably tried enough in terms of fixing it, but i have noticed that this effect isn't shown in tabs such as 'Texture paint' 'shading' and 'animation' so i think its only an issue within UV editor.
here's the link to the video if you want to see exactly what i did: https://www.youtube.com/watch?v=1jHUY3qoBu8&t=236s
the part that i'm talking about is around 2:10 and goes till 4:50.
Cheers :D
edit: added photos