Is that normal practice in any style of aikido, to have rank newbies participate in exam-prep classes? I feel very apprehensive of returning to the dojo, also very apprehensive of getting scolded again for something that I'm really not sure should be my fault.
We tend not to extend our newbies too far ahead of themselves. We want to take care of them so they want to return and they remain unharmed.
We don't have special exam-prep classes so unsure of your context. Accidents do happen when the mats are too crowded.
IMHO, it is your Sensei's and Sempai's responsibility to help you train wisely and safely, as well as your own.
Talk with your Sensei. If it continues, train elsewhere.