It doesn't take much. I once put my name, job title and employer on LinkedIn. That was enough for someone to email my payroll officer and convince them to change my paycheck to a different bank account. I had no idea until my pay was missed.
My payroll officer was a dumbfuck, but that's all it took.
I'm very sorry that happened to you. But honestly, I don't see that as an issue with privacy. More like gross incompetence at your workplace and you paid the price of it. Hopefully it didn't affect your day to day too much.