This plugin was last updated 10 months ago. So I wanted to know are you still providing support for this plugin?

Before decoding id_token using base64, the base64 code should be URL decoded:
https://www.php.net/manual/en/function.base64-decode.php#118244

oauth_handler.php
now is:
$id_body = base64_decode($id_array[1]);
and in some cases it doesn’t work, because there are “_” and “-” in the base64 string.

should be:
$id_body = base64_decode( str_replace(array(‘-‘, ‘_’), array(‘+’, ‘/’), $id_array[1]) );