4plex roof ventilation question.

[Gregory London]

Hello all, I own a 4plex in Louisiana and I know it has 4 vents on the roof, but the vents don't have a protected cover going from the upstairs bathroom out of the roof.

So I think the vents just suck up the hot air and it seeps out at any one of the combined 4 vents.

Question:

Is this normal in a 4plex or should there be a tube the air goes up?

Don't see any mold issues, I'm in the process of replacing one of the vents now.

Thanks in advance!