Vitrified egg cells do not necessarily lose their quality. However, it is different if the quality of the oocyte before vitrification is not the best. If the oocyte is not of good quality, the freezing and thawing process can obviously damage it.
If they are good quality oocytes, there is no reason why there should be any kind of problem. It depends more on the quality of the egg before being frozen than on the freezing technique itself.