Cookies burned on bottom

Here's an old thread about those insulated pans. https://food52.com/hotline/4533-insulated-baking-sheets-what-do-you-use-them-for-if-anything-other-than-delicate-cookies-and-the-l

I think dark pans can cause the bottoms to brown more than shiny pans

Usually a result of too high an oven temp (the thermostats are not to be depended on) or too long a time. They'll tend less to do this if you cook them higher in the oven, too. In desperation, you could use one of those insulated, two layer cookie pans, but the cookies won't really cook properly- they SHOULD brown some on the bottom (most types, that is).

It happens. Use a 'airbake' sheet pan to help buffer it.
Also..cookies can be trickey about when their done. They're always pretending 'oh cook me more' when you just need to take them out and let them cool.