Moisture?

[Jdeal1]

This is my bathroom I feel like the fan is causing this or the design of the bathroom. We shower with the door open and leave the fan on for at least 30 minutes after ahoeering.
How does this get fixed

 

[Snoonyb]

Why do you suspect the exhaust fan is the cause?
Is the entry door to the room left open or closed, while the exhaust fan is on, and where is the door in relation to the fan?
How is the room conditioned?

 

[Jdeal1]

It’s about 7 feet from the fan

 

[Snoonyb]

Thanks.
Assuming the ceiling register is a supply, not a return. If it's supplying during the exhaust period, it will affect the efficiency of the exhaust, which can be mitigated by installing a register, or exhaust fan, above the shower stall, switched simultaneously, and augmenting the existing vent, as opposed to an additional roof or soffit penetration.

That is what I would do.

However, you could change your routine, or apply an epoxy finish to the ceiling, as other alternatives.

 

[DFBonnett]

I had good results with both Zinsser Perma White and Ben Moore Aura Bath & Spa for this type of problem.