Both for encoding and decoding the padding is not needed. Without ='s, you get a uniquely different base64 encoding for NULL, 2 NULLs and 3 NULLs.

This shows the binary, base64 without padding and base64 with padding:

NULL --> AA --> AA==

NULL NULL --> AAA --> AAA=

NULL NULL NULL --> AAAA --> AAAA

As you can see, all the padding does is make the base64 length a multiple of 4. You already get uniquely distinguishable symbols for the 3 cases (one, two or three NULL symbols) without the ='s, so they are unnecessary