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.
Yea, I've put electrical tape on electronics before (wait, what!?) and yea, it just peals off after some time. Never thought of using a permanent marker, ill give that a try now.
I have older 003 raisers and they don't have LEDs. But I have problems with video cards, because in Hive OS, backlighting is not turned off for all video cards. Some video cards glow like сhristmas trees. I used Double-sided 3M. It's very reliable.