Im using "Intel(R) HD Graphics 5500".On an unrelated note,the fact that you care this much about fixing someone else's problem is really respectable!
Hey sorry for the super late response on this. I think I have a fix: Can you try downloading this version of the game from this link?:
https://abhimonk.itch.io/spectral-slash-lighting-fix?secret=3xLTIItqjm77Vi3Lf0uvClb0BY
I made some changes to the lighting shader that I think will hopefully fix the issue for you. If you have the time, can you give it a try and let me know if it works?