Here’s the money part:
No use of potassium bromate.
I wish I could store 50lbs. I have to put flour in the fridge or it gets weevils. I’ve tried everything for dry storage, but they still come.
Years ago at an aution hug bought two HUGE ceramic crocks, with lids. We have a pantry room which stays cool in the summer, with a small A/C in case it warms up above 60. White and whole wheat flour keep fresh. You’re in FL so... Maybe a small room with A/C might help flour stay fresh and bug free.
They were almost certainly in the flour when you bought it, just too small to detect. The refrig inhibits their reproduction for a time. For dry storage you would likely need to seal them with an oxygen absorber inside - until needed.
Take a sample of a batch/container and try putting that in a sealed container with a small chip of dry ice and see if that works.