This is normal. Of your 5.8 BAT, you appear to only be receiving around 3.7 BAT for your payment. The 2.036 or so that you see for Current earnings this month (estimated) is the balance that “rolled over.”
This happens when not all ads reconcile prior to the end of the month. As to the “missing” BAT, that’s what you’ll receive whenever your payment arrives (which is after the 8th of the month and can take a while to receive).
It might help you to read through the FAQ at -Retired- PSA: User FAQ - Support & Answers