Poor girl, I understand COMPLETELY! I can't go on one of these video calls or whatever they are called. They terrify me to the point of being sick. No reason, it's just a phobia. Add to that your DG is dyslexic, and in not surprised. The school is aware of her difficulties and under normal circumstances would be providing her with support in class. Clearly this isn't possible but there's no reason why she can't try to access the claim a sees with just a little support.
Would she join the class if she couldn't be seen? If so, just angle her screen so t h at she can talk but not be seen, (put a teddy in her place or similar), & could her carer help with lessons?
Whatever the solution, her difficulties should be recognised, and she needs support not criticism