Received leaver penalty in ranked solo q lobby due to person leaving on other team? (Client Issue)

So I just joined a ranked solo que lobby and I was fourth pick. The person on the other team was going to pick azir but the time limit reached 0 and we ended up staying in the lobby for another 5-10 seconds before he left and I ended up getting the penalty instead. This seems like a huge problem that seems unaddressed.

Steps to reproduce:

1. Join a ranked solo/duo que lobby

2. If someone on the other team looks like hes going to dodge because he did not lock in his champ check to see how long it takes for the lobby to close and then see if you received a leaver penalty

This is the first time I have encountered this client bug.

Could not provide any screenshots or videos to show the issue due to not recording.