MD5 and SHA-1 were designed to be cryptographically secure hashing algorithms. While fairly fast for small files, comparing large numbers of large files can become prohibitively slow, which is what leads me to request an implementation of a faster, non-cryptographic hash algorithm meant for file comparison. The fastest I've found is xxHash3.
Considering that the collision risk of xxHash3 is acceptably low even in combinatorial situations (where each hash is compared to all other hashes), the risk of collision in a one-to-one scenario such as file comparison should be negligible (~3.14 collisions per billion comparisons).
I'm not a programmer so I'm not sure how difficult it would be to include in rclone, but the github page seems well-maintained and the developer seems to be actively supporting it, so that seems to be a good sign.
Please let me know what you think.