Thanks for confirming. Bingo, songbird is not yet compatible with 2020.11, as there is a dependency conflict related to tensorflow I believe... see here:
This is one advantage of using conda — you can install parallel environments for different QIIME 2 releases or to support plugins that clash with each other. So you can have a parallel 2020.8 environment for when you want to use tensorflow... and another for 2020.11... and maybe another development environment... etc...