Did you bid into a new classification? If so then your pay will be adjusted based on the new classification. Red circle means you won't earn less if you don't bid into a position with a lower top out than you already make.
I have to scratch my head that you'd be making more than something around $28 an hour as a pter and not know these things. To be red circled as a pter you've had to be here for a long time afterall.
Edit: If there's a progression for the position you've bidded into you won't drop down to the progression, you'd stay at your rate until the progression caught up. The limited information you've given says you bid into a position that has a lower top out than you currently make. Think of a pc driver who bids into a 22.3, they don't keep the driver wage but go down to the top out rate for 22.3.