Not illegal.
The company name registered in the industrial and commercial registration can be inconsistent with the name of your brand, but your brand needs to register a trademark, and the relevant scope of your business area must be protected. As long as it is registered If it is legal, it will not be illegal.
As long as the name has nothing to do with other people’s restaurants, it is allowed locally. If you are the same as others, this is called infringement of other people's rights and interests, which falls within the category of unfair competition and is illegal.
For detailed information, please refer to Article 9 of the "Advertising Law of the People's Republic of China". Normal naming does not hinder social stability or harm the interests of the public and the dignity or interests of the country. Leaking state secrets is allowed.