Instant_damage effect called from custom entity's behavior animation applies itself four times

Verification builds: 1.16.102.0 build 4328820

Summary: Instant_damage effect called from the behavior animation on custom entity is applied 4 times instead of once.

Impact: The intention is that instant_damage effect is called only once, applied once and player loses 3 harts.

Repro Steps:

1. Create a custom entity that uses animation
2. At one point in animation timeline, add command /effect @a instant_damage 1 0 true.
3. At the same point in timeline add command /tell @a TEST

Observed Results:
The effect command is applied 4 times to players - each time player will lose 3 harts.
Tell command will display TEST only once.

Expected Results:
The effect command should be applied only once. Player should lose only 3 harts.

Screenshots/Videos attached: Yes.

https://drive.google.com/file/d/1_M9GF3JIYOt0X5V26VTVEkMJn9mCJxMV/view

Notes: This does not happen with wither effect, for example. When the same command is called in chat, the player loses 3 harts only once.