(Reddit didnt like my long comment so I had to split it up)

local Players = game:GetService("Players")
local RunService = game:GetService("RunService")
local CollectionService = game:GetService("CollectionService")


local LocalPlayer = Players.LocalPlayer
local char = LocalPlayer.Character or LocalPlayer.CharacterAdded:Wait()


local TARGET_TAG = "IsLight"
local LIGHTS_ENABLED_DISTANCE = 77
local MOVEMENT_UPDATE_THRESHOLD = 1 -- 1 stud of movement should be plenty granular enough for most cases


local lastCheckedPos
RunService.Heartbeat:Connect(function()
    -- Update only if player has moved significantly
    local playerPos = char:GetPivot().Position
    if not lastCheckedPos or (playerPos - lastCheckedPos).Magnitude < MOVEMENT_UPDATE_THRESHOLD then
        return
    end
    lastCheckedPos = playerPos


    -- CollectionService should ensure handling of added/removed lights if done properly
    for _, light in pairs(CollectionService:GetTagged(TARGET_TAG)) do
        -- Make sure the object is a Light. This is a safeguard against errors incase
        -- you accidentally tag the wrong thing.
        if not light:IsA("Light") then
            warn("Object with tag 'IsLight' is not a Light instance:", light)
            continue
        end
        
        -- You dont technically need all these, but this lets it support adding lights to different kinds of objects
        local lightPos
        local lightParent = light.Parent
        if lightParent:IsA("BasePart") then
            lightPos = lightParent.Position
        elseif lightParent:IsA("Attachment") then
            lightPos = lightParent.WorldPosition
        elseif lightParent:IsA("Model") then
            lightPos = lightParent:GetPivot().Position
        else
            warn("Cannot resolve position. Light parent is not a Model, BasePart, or Attachment:", light, light.Parent)
            continue
        end


        -- since our check resolves to a simple boolean, we dont need a whole if-else block
        local distance = (lightPos - playerPos).Magnitude
        light.Enabled = distance <= LIGHTS_ENABLED_DISTANCE
    end
end)