This is a little hard to explain but basically, there is a minor difference between player commands and command block commands when ran.

The most noticable way I can show this off is via /data

How to reproduce:

1./data merge a skeleton or a zombie while they have a target with a command block set on repeat

2.do the same thing but with player commands or data packs

Observation:

When the /data is ran via command block, the zombie or skeleton's behavior is not interrupted, while player ran or data pack ran commands causes the mobs to freeze

Expectation:

Like command block ran commands, they shouldn't freeze in place when getting /data'd

 Command used: /data merge entity @e[type=skeleton,limit=1,sort=nearest] {false_value:false} (I recommend using a false value like what I did to not completely affect the mob's state when testing)