On a grey or more colorless site it's recommended to use colors that give high contrasts to each other in order for the user to have a better experience aswell as being abled to control the user's behavior better.
Since I couldn't find any mantine theme generators (btw. another cool little project idea if you think about it), you could at least use pages like [this] to get inspired by popular color palettes and then build a custom mantine theme yourself.
Eko450-eng
commented
1 year ago 
lkuessner
On a grey or more colorless site it's recommended to use colors that give high contrasts to each other in order for the user to have a better experience aswell as being abled to control the user's behavior better.