Has he changed his style of design/lay-up recently (or the size of the pieces)? One of the things you will notice is that all of the large bubbles, and many small bubbles, lie along the lines of the flower stems and the thin blue border. It is hard to tell, but my guess is that these design elements are sandwiched between two layers of glass. Even if these are painted enamels, this creates a prime area for bubbles to form. If they are glass elements sandwiched between two other layers, you most certainly have conditions for trapped air.
Also, if I have converted the firing schedule correctly (my brain thinks in Fahrenheit, especially when it comes to ramp rates!), you are ramping very quickly to a temperature that is just below a bubble squeeze. By my calculation, you are ramping at 621 deg F to 1202, holding 45, and then ramping 400 deg F to 1490. There is no proper bubble squeeze in this schedule. I work in System 96, but a typical schedule for me is:
200 to 300 deg F/hr to 1000, hold 30 minutes
50 deg F/hr to 1250, hold 60
200 to 400/deg F to process temp (for me, typically about 1460)
Stopping at 1000 degrees and holding allows the temperature of the glass equalize just past the strain point. The very slow ramp up to 1250 and the long hold allows the glass to begin sagging in the middle first and moving out toward the edges, pushing the air with it as it goes, before the edges seal. If he has side elements in his kiln and your smaller one has only top elements, or, if his kiln can heat more quickly to temperature than yours, then that might be why you see a difference in the two kilns (not to mention temperature differences).
You don't mention anything about the lay-up of the glass, so this is just my best guess. Additional information might change my answer
Also, a word of caution. You are annealing at way too high of a temperature at 1004 deg F; Bullseye glass recommends 900 deg F (482 C).
Best, Dana W.