Decoding flatfs filename to get cid

I am using flatfs with: "shardFunc": "/repo/flatfs/shard/v1/next-to-last/2"
So for example there is a file named:
in the ipfs datastore. from what I read in documentation, the cid should be just adding a B to the beginning, but it seems wrong as it gives Invalid CID version 30 . can someone help me decode this filename to the cid hash?

ah found it. filename is DIGEST (BASE32 MULTIBASE): bdyqjmbzi47o5j4ihwqfslemmpeun2bpytz6xpi4bksc6tobfrtojumq