Extra Day Duration?


I'm confused. This is my first time using Smartsheet for scheduling. I think I have an extra day appearing in each of my durations?

ID 88 depends on ID 80, which completes on 6/17/24.

ID 88 is a 5 day duration showing it is starting on a Monday 6/17/24 and ending Monday 6/24/24? Isn't that 6 days?

I'm expecting to see either ID 88 show that it is starting Tuesday 6/17/24 ending on Monday 6/24/24 - Or - starting Monday 6/17/24 and ending on Friday 6/21/24.

I feel like I'm missing something very obvious.