The redstone glow effect does only work on signalstrengh 15 and 14 but not on all lower ones.
So it looks like there is an bug with redstone wire... only the signal level 14 and 15 gets illuminated correctly...(i using Solas Shader V1.5, the newest version on modrinth, and i use the 1.18.2 with optifine)

this problem still exist in the newest shader release. also i postet this problem in the discord. i use the faithfull texture pack that i editet a bit ... but redstoneblocks dont glow at all, only a single pixel does light up. its very strange why it does that. in solas 1.6 it didnt have this problem. it happens on fabric and also on optifine/forge.