Exactly what the title says. When you summon an area effect cloud with RadiusPerTick:0, teleporting it doesn't update its real position, but if you check it with

/data get entity @e[type=area_effect_cloud,limit=1] Pos

it shows the position it is meant to be at. However, there are a few quirks that I've found, including killing an entity riding the bugged area effect cloud causes it to drop its loot at the position it is meant to be at. This also occurs in 1.16.3, but I haven't tested it for other versions.