I have tried replacing the torch in the config with the id of a different lightsource that dosent drop anything to circumvent duplication of torches but when I tried, it still places torches

This has been an issue for a while now and is still the case as of 7.4.8

Non critical issues for 1.20 are no longer being handled, and the feature works as expected in 1.21. The code for that config hasn't changed though, so I'm surprised to hear that it's broken. Does it work if set to minecraft:glowstone?

If the input item is invalid or malformed it will default back to a torch, so you may want to double check.