It's a bit of a stretch to call this one "vanilla-friendly", but for over a year, players on my SMP, Kamacraft, have been asking if I can add an end-game item that will keep mobs from spawning. So here we are.

This datapack DOES NOT MODIFY NORMAL BEACON FUNCTIONS.

Instead, this datapack makes it possible to upgrade your beacons. Once upgraded, they will instantly vanish any of 31 different mobs (see the video for the complete list) as soon as they appear throughout the entire beacon range. The datapack bases itself off the beacon's own data, so the range adjusts automatically and quickly as you add or remove layers.

Note: mobs that are killed by the beacon will not drop loot.

This is intended to be an end-game item, but my server hosts a large range of play styles, and to keep this within reach of all players, I admit I nerfed the cost a little bit.

To upgrade your beacon:

You'll need 81 diamonds crafted into 9 diamond blocks (not mentioned in the video, but netherite blocks function as well). You will also need 1 netherite ingot you are ready to sacrifice.
Replace the top layer of your pyramid with your diamond or netherite blocks, and throw the netherite ingot on top of the beacon itself.

If you've upgraded the beacon correctly, your netherite ingot will disappear, and the beacon will change appearance.
That's it! You are now free to recover your diamond or netherite blocks, and replace them with whichever beacon block you prefer. The beacon will also continue to function as a normal beacon in addition to its new duties.

BE SURE WHERE YOU WANT THE UPGRADED BEACON. ONCE UPGRADED, BREAKING THE BEACON ITSELF WILL REMOVE THE EFFECT, AND YOU'LL HAVE TO DO IT ALL OVER AGAIN.

Despite the fact that the beacon changes appearance, the datapack does not require an accompanying resource pack.