Reminds me of https://archive.org/details/banned-cartoons

It could be that making kids’ content with historical settings could be too fraught to bother with: either you include the problematic stuff and people get mad at you for exposing kids to it, or you exclude it and people get mad at you for whitewashing history.

Or (perhaps more likely) such shows are still being made and you just haven’t noticed. “Peabody’s Improbable History” may no longer be around, but kids today have “Xavier Riddle and the Secret Museum” instead, for instance.