No need to specify $(package)_download_file when it is equal to $(package)_file_name.
Historically, before bitcoin/bitcoin#19817, distinct $(package)_download_file and $(package)_file_name were used for better portability (I guess) by removing + characters from a file name.
The only package which still use file renaming is native_capnp: https://github.com/bitcoin/bitcoin/blob/eca694a4e78d54ce4e29b388b3e81b06e55c2293/depends/packages/native_capnp.mk#L3-L5