If there is no company information involved, including no harm to the unit, it is not considered infringement. If you want to sue you for infringement, you need to prove that you have used the same or similar trademark as its registered trademark on the same or similar goods, or that your use of this account has harmed the legitimate rights and interests of the trademark owner. However, it is recommended not to use the work account after leaving the company. I also do online promotion at the company. Generally, the account is company information. If you resign, just log off the account.