Entity moves when your are or not looking at it

1. Create Procedure

2. Set Event Trigger to "On player tick"

3. Add command block with the command execute as @p at @s anchored eyes facing entity @e[distance=..25,type=modid:entityid] eyes anchored feet positioned ^ ^ ^1 rotated as @s positioned ^ ^ ^-1 if entity @s[distance=..0.35] run effect give @e[type=modid:entityid] minecraft:slowness 1 255 true

4. Example

https://www.youtube.com/watch?v=0ruq38KmcSs