There is a fork for 1.21+

https://www.curseforge.com/minecraft/mc-mods/beacon-conduit-tweaks

This mod adds configurable mechanics around range

Beacon Options:

• Default range
• Added range per level
• Added range per block of certain type

Conduit Options:

• Added vanilla range
• Added range per block of certain type

This allows for a wide variety of possible configs including the use of certain blocks / levels reducing the range
By default it makes emerald/diamond blocks add 0.5/block and netherite 2/block to beacons, doesn't change conduits.

[Server-side mod]