Collaborations during Mental Health Duress
That's a pretty big "if" @YemonChoi has there.

Yes, ideally there should not be a stigma. But realistically, even if your collaborators are professional enough not to stigmatize you, are they also professional enough not to mention such a communication to others?

What has been said cannot be unsaid.

I would recommend to let sleeping dogs lie. As long as nobody has complained, you don't need to explain yourself. (Maybe people not only didn't complain, but also didn't even notice lower productivity on your part - your productivity may have been just fine for your collaborators. Consider the "impostor syndrome".) It's better to work on your issues than to explain them.

Good luck!