It is implied by not allowing to work from home. There wouldn't be a need to work from home if it was a 9-5 job.

For most of us, "work from home" means doing your regular work, during your regular hours, from your home office. No additional hours are implied.

Before covid, working from home wasn't really a thing at the company I work for. That meant I arrived at the office some time before 10, was there for around 8 hours, then left. That's what "not being allowed to work from home" means to most people.