What a pity! The right side was looking so good! The learning stages for FMQ are full of these unpleasant surprises, but they do decrease as you have more practice.
What you have here does look like a threading problem, but tension is also very important in FMQ. The top tension should be lower than usual. The bobbin tension in my two machines (a Bernina Aurora and a Pfaff Grand Quilter) is more complicated. I check that, when I hold the thread coming from the bobbin and gently shake it, the bobbin moves only a little.
I wish that I had been able to read this site as I was learning FMQ - I've seldom felt such a dunce in my life, so uncoordinated and it would have been reassuring to know that others struggle too. Some lucky people learn almost instantly, but the rest of us just have to hang in there.