Yeah I had this issue in the past but it wasn’t with risers it was with Bitcoin ASICs and they were worse because they weren’t permanent solid like a riser LED they blinked consistently. I had them in my room and at night they drove me nuts.

Basically you can try tape but it will fly off due to the heat. So if that doesn’t work and you don’t want to desolder them one by one then use a black permanent marker. You will still see it somewhat but won’t be as bright as before.