I attend a local gym. I've generally not had a major issue with the idea of mixed gender bathrooms provided they are fully enclosed with sink in with the toilet and our local pool has village changing which I'm fine with although I understand the reasons why other women may not be OK with this and prefer single sex. But, the gym changing is serviced by a male cleaner and it has communal changing ie no cubicles so it means I feel i can't change to go after/ before work and I definitely don't feel comfortable using the shower because I've no idea when the male cleaner will come in to clean them which he seems to do roughly hourly during the day. The door opens straight into the changing room and showers are separate so if you were in the shower you wouldn't know he'd come in until you were in the same room. The showers have curtains rather than cubicles.
I'm tempted to email my gym but tbh I feel really uncomfortable with the idea that I could effectively jeopardise this guys job.