Looping sounds have a loop segment that is different from the others

I was in creative mod on a superflat world, and it started raining, i noticed that the sound had a segment of the loop different from the others, creating a strange effect.Then i tried flying with the elytra and same story. Afterwards i noticed that all game sounds sound like that

What I expected to happen was...:
The sound would loop like normal

What actually happened was...:
It looped, but added a new segment to the loop

Steps to Reproduce:
1. Create a new superflat world(default)
2. Create some sounds repeatedly(Rain,Elytra,intense block placing, music discs)
3. Listen to the sounds

Help me find other versions that have this issue! Best if headphones are used!