When I try and load a moded server using this mod as well as some others (such as backpacked, tetra, etc.) but is crashes and says "Backpacked only supports curios 4.0.1.0 or above"
"Currently, curios is 1.16.5-4.0.5.1"
curios is definitely above the required version. But it doesn't realize it...

I believe this was fixed from Backpacked's end, make sure you've downloaded the latest version.