Actually tested in je 1.21.3，I don't know how to select version 1.21.4 in the affected versions list

Case A:

1.Summon a marker with a specific uuid 0-0-0-0-9

/summon minecraft:marker ~ ~ ~

{UUID:[I; 0, 0, 0, 9]}

Check:

/execute as 0-0-0-0-9 run say 1

2.Throw a lingering potion to create an area effect cloud

3.Set nbt "owner" with command /data

/execute as @e[type=minecraft:area_effect_cloud] run data modify entity @s Owner set value [I; 0, 0, 0, 9]

Check:

4.execute on origin

/execute as @e[type=minecraft:area_effect_cloud] on origin run say 1

As expected, the marker should have executed "say 1", but its initial owner executed "say 1"

 

Case B:

1.Summon a marker with a specific uuid 0-0-0-0-9

/summon minecraft:marker ~ ~ ~

{UUID:[I; 0, 0, 0, 9]}

Check:

/execute as 0-0-0-0-9 run say 1

2.Summon an area effect cloud with a specific owner 0-0-0-0-9

/summon minecraft:area_effect_cloud ~ ~ ~

{Owner:[I; 0, 0, 0, 9], RadiusPerTick:0, ReapplicationDelay:0, Duration:2147483647}

Check:

3.Execute on origin

/execute as @e[type=minecraft:area_effect_cloud] on origin run say 1

As expected, the marker should have executed "say 1", but nobody says 1