Permissibility of personal name change in business

Slms if a person left a job and then was not allowed to work in that field for 2 years due to competiton/ regulation rules but they worked under a diff name. But now the 2 years have passed can they still work under that diff name instead of their birth name as the clients that person has gathered knows the person under the diff name.
Pls note the persons wages were under their real name and tax also was paid under the real name. Only when speaking to clients the person used a diff name.
Pls kindly confirm the following:
A)Is a person sinful for not following the rules of this employment field.
B) will it be a sin for the person to continue using the diff name and not their birth name and if it is a sin then pls kindly confirm the best way out by the person maintaining the clients and also not committing a sin.

C)Or is it best that leave the diff name with the existing clients, repent and moving forward all new clients the person gives their real name.
D) the person makes intention that the diff name is their nickname and then just maintains that name and gives that name to all the clients.

Pls kindly confirm


May Allah bless you.
It is not permissible to deceive others in any ways. Hence, I would advice that this person does istighfar and moves forward by doing business using the correct information.

And Allah knows best!