Hey Kai,
Thanks for reaching out!
The best resource for functions is the code of the plugin itself: I would encourage simply opening up the plugin code in a code editor and reading it all through.
For an abstracted resource, though, the best one is this list of plugin functions → https://theeventscalendar.com/functions/
That list shows both non-deprecated functions and deprecated ones, and there is unfortunately no way to filter the list down to only non-deprecated functions, but all non-deprecated functions are listed there.
I hope this information helps!
George