I haven’t had a problem with NSFW content when that setting was turned on. There are occasionally shirtless pics of men There’s also a lot of clothed anime titties (think Lara Croft).

If you’re really worried about what your children are going to see, you really should installed some sort of parental filter software. BlueSky is not the only app that can expose children to adult content.

I believe there are also a lot of pre-made blocklists you can set up on blue sky that might help you. Though I have not tried that myself yet.