Not sure if this is a Solus or a Steam related issue. When using Steam in home streaming, Intel hardware decoding, which uses Intel VAAPI doesn't work at all and failover to software decoding instead.
Probably related to this steam issue: https://github.com/ValveSoftware/SteamOS/issues/338
The solution provided in the steam thread is to remove steam libs and switch to system native ones.
I used Linux Steam Integration to ensure steam uses OS libs but same results.
Obvisouly, I can test or show better outputs for this.