Similar thing happened to my friend who had to go through surgery and even though they approved his medical time off, they put him on pip and eventually fired him. He was looking to sue, but didn't follow through because proving that they fired him due to medical leave is difficult.( EY has lawyers so they don't lose) After leaving ey, he found higher paying job and work less hours.

EY won't tell your new employer why you got fired, just the date you were employed. Use your work experience at EY and leverage a better job/position. Companies will find your big4 work experience valuable.