One reason I took the T3/T4 was that I had been taking iodine supplement, apparently I took too much and it was starting to shut down my thyroid.
My TSH went up to 3.0 and FT3 went down to 2.1 (2.0 - 4.4 range), which is nearly clinically hypothyroid.
So I am more careful with any supplement that are "high" potency. Last time I measured my Vit D levels, I was at 90.6 (30-100 range) in July 2019 which is nearly over range on vit D levels, so I stopped all vit D supplements. C0Q10 levels were 2.19 (0.37 - 2.0 range).
I worry about too many supplements Vs not enough.