[Calamath]

There are many ways to detect warping between different zones using fast travel, but I use EVENT_PLAYER_ACTIVATED.

Here is a hint.

local isFirstTimePlayerActivated = true
 
local function OnPlayerActivated(eventCode, initial)
    if initial then
        if isFirstTimePlayerActivated == false then
            -- --------------------------------- after fast travel
            -- do something
        else
            -- --------------------------------- after login
            isFirstTimePlayerActivated = false
        end
    else
        -- ------------------------------------- after reloadui
        isFirstTimePlayerActivated = false
    end
end
 
EVENT_MANAGER:RegisterForEvent("yourAddonName", EVENT_PLAYER_ACTIVATED, OnPlayerActivated)