I have had low thyroid function for 30 years so I try to read about food and thyroid function every so often. Just this morning I read these two posts on the subject that don't exactly answer your question but provide some useful background information.
https://www.thethyroiddietician.com/is- ... r-thyroid/https://www.mayoclinic.org/diseases-con ... q-20058554A dietitian I consult with occasionally assured me a year ago that I would have to eat big heaps of cruciferous vegetables every day in order for a detrimental effect to become measurable. I assured her that I could easily fall into a routine of eating big heaps of them every day, so should I try not to? She told me to eat what I want and let her know if I notice abnormal hair loss, unusually dry skin, onset of depression or lethargy...or if my thyroid blood tests take a marked turn for the worse.
So far, so good, but clearly it's a sensible question to ask. Maybe someone here has actual experience with broccoli and other cruciferous interference with their thyroid and will share some details.