If it is illegal there are a lot of people breaking the law right now, including me.
There is a distinction between working from home in an apartment and running a business from an apartment. That is – you can’t run Zumba classes in an apartment, or have a business that has numerous clients coming and going from the apartment (there are degrees there). A range of considerations apply to running a business including council regulations and liability insurance. Bear in mind that a tenancy agreement may specifically prohibit running a business from an apartment (or a house).
But if you are just sitting in an apartment working on a computer and having Zoom meetings, you are not doing anything illegal. That is working from home, not running a business.