It looks like a newer version of the sport loop which I wash regularly. Either washing machine or if I’m in a hurry, I wash it under a warm tap with normal liquid soap.
Apple say…
For Solo Loop, Braided Solo Loop, Sport Band, Sport Loop, Ocean Band, Alpine Loop and Trail Loop:
Wipe the band clean with a non-abrasive, lint-free cloth. If necessary, lightly dampen the cloth with fresh water. With these bands, you can also use mild hypoallergenic hand soap for cleaning.
Dry the band with a non-abrasive, lint-free cloth before you attach it to your Apple Watch.