Still playing older versions, but don't want to exploit raid farms?
No problem!
Just drop this datapack into your world and build a witch farm to get insane amounts of redstone. Supports versions 1.13 - 1.20.6, in 1.21+ this is a Vanilla mechanic.
With this pack enabled, witches will drop 6 redstone on average, with 7.5 average if you have Looting III.