When attempting to store values of UUID Least and Most (long) obtained from /execute, the resultant value to be stored becomes limited with values similar to that of /scoreboard (-2,147,483,648 to 2,147,483,647).

Example:

Command:

/execute as @e[type=minecraft:slime] store result entity @e[type=minecraft:item, sort=nearest,limit=1] Thrower.L long 1 run data get entity @s UUIDLeast 1

When testing the updated entity:

/data get entity @e[type=minecraft:item,sort=nearest,limit=1] Thrower.L

Output:

2147483647L

A similar output is observed on Area of Effect Clouds as well.