The Problem of Lingering Potion Duration

/give @a minecraft:lingering_potion[minecraft:potion_contents={custom_effects:[

{id:"minecraft:wither",amplifier:0b,duration:1600}

]}]

From 25w02a to 25w04a, get duration of 1600gt lingering potion, in the inventory display 20 seconds, actual effect for 20 seconds;
On 1.21.4, get duration of 1600gt lingering potion, in the inventory display 20 seconds, actual effect for 80 seconds;