Not true. If you have fallen behind you will acquire them through M+, Raids, or PvP wins.
From PvP, they come out of the victory boxes you get from winning an arena or BG.
You can use this command in-game to see how many you have out of the maximum currently available.
/run a=C_CurrencyInfo.GetCurrencyInfo(2800) print("You have earned " .. a.totalEarned .. " of " .. a.maxQuantity .. " possible Splintered Sparks of Awakening")