Flickering light emitting from mobs+player.

Hi. After updating Minecraft to 1.21.3 along with iris+sodium, i am getting this weird glitch coming from mobs whenever i have the option ‘real-time shadows’ enabled on the voxlementary shader. I know it is an outdated shader but I don’t get on with its successor and it worked fine on 1.20.4 and when running through optifine, this issue is not present, leading me to believe it could be Iris related. Tia.