thanks for the reply that did not answer the question asked.
Any analysis about how hard it is for an attacker to get a file on your local file system via a cloned got repo, cached file, email attachment, image download, shared drive, etc is just a distraction.
BLAKE 3 is faster only in wall clock time, on an otherwise idle computer, because it fully uses all CPU cores, but it does not do less work.
BLAKE 3 is preferable only when the computer does nothing else but hashing.
On a modern intel CPU, one core of SHA1 does about 500MB/s worth of hashing. Blake3 on the same core is 1.5GB/s or faster.