[nevcairiel]

You should be using Profile 0 (Main) for 10-bit 4:2:0 for maximum compatibility.

The general AV1 rules are pretty simple:
Main Profile (0) is 8/10-bit 4:2:0 or Monochrome (4:0:0)
High Profile (1) is 8/10-bit 4:2:0, 4:4:4, Monochrome
Professional Profile (2) is 8/10/12-bit, 4:2:0, 4:2:2, 4:4:4, Monochrome

I would assume that the encoder follows the same rules - and judging by that message it even enforces the "use the lowest profile possible" suggestion?
I don't know right off the top of my head if the profiles actually influence anything else beyond the bitdepth/chroma, but I don't think so, which gives you little to no reason to use a higher profile when you don't need its chroma/bitdepth extensions.