(1.14.4) Custom Potion effects not working

Im trying to make it so that players get a potion with custom effects when they join.
It gives them the potion with the custom name when they join, but the potion doesn't have the custom effects.

Here's my code.

Code:

@EventHandler
public void onPlayerJoin(PlayerJoinEvent e) {
Player p = e.getPlayer();
ItemStack magic = new ItemStack(Material.POTION);
PotionMeta magicmeta = (PotionMeta) magicgetItemMeta();
magicmeta.setDisplayName("§2magic potion");
PotionEffect effect = new PotionEffect(PotionEffectType.SLOW, 600, 1);
PotionEffect effect2 = new PotionEffect(PotionEffectType.SLOW_FALLING, 600, 1);
PotionEffect effect3 = new PotionEffect(PotionEffectType.INCREASE_DAMAGE, 600, 1);
magicmeta.addCustomEffect(effect, true);
magicmeta.addCustomEffect(effect2, true);
magicmeta.addCustomEffect(effect3, true);
magic.setItemMeta(magicmeta);
p.getInventory().addItem(magic);
p.playSound(p.getLocation(), Sound.ENTITY_VILLAGER_WORK_CLERIC, 100, 1);

}