I received an email from Airtable after I submitted the same question via the help bot. This is the way the Airtable bills when you add a new editor. When I initially paid I purchased 6 seats (I thought I had purchased 7), then I added an 8th.
The way to read this is the initial purchase was 6 seats from 10/23/23 to 10/13/24. That was changed to 7 seats from 10/23/23 to 10/13/24. Then on October 26th I added the 8 seats so the new bill is for 8 seats from 10/26/23 to 10/13/24.
The thing that threw me was the 6 to 7 seats as I had 7 editors when I purchased. I'm not sure why I only paid for 6 initially. The other odd numbers are just pro-rating. This bill subtracts the initial 6 seat payment I already made, adds on a 7 seat payment, then takes that away (prorated for the days that the 7th seat was active) and then gives the annual total for the 8 seats.
It is a little odd, but I suppose makes sense.