Syncing two "raw" remotes without common Checksum Hashes

What is the problem you are having with rclone?

I’m getting this notice:

START sync koofr:RCE -> hidrive:users/xxxx/RCE
NOTICE: HiDrive root 'users/xxxx/RCE': --checksum is in use but the source and destination have no hashes in common; falling back to --size-only

Now I do understand that there are NO COMMON hashes between koofr and hidrive. Fine.

But I’m running this on a VPS with two “remote” remotes, not a local one.

So my question is: Why wouldn’t it be possible to check checksums during the transfer on the VPS side? Since the data has to pass through the VPS anyway (download from Koofr → upload to HiDrive), rclone could theoretically calculate a hash locally after downloading from the source to make an integrity check with the source; and then calculate the second “target” hash and check it after the upload to the destination, as a secondary integrity check!?

Run the command 'rclone version' and share the full output of the command.

rclone v1.73.2
os/version: debian 13.3 (64 bit)
os/kernel: 6.12.73+deb13-amd64 (x86_64)
os/type: linux
os/arch: amd64
go/version: go1.25.8
go/linking: static
go/tags: none

Which cloud storage system are you using? (eg Google Drive)

Running the following rclone command on a VPS, backends being Koofr and Hidrive, both raw without crypt layer.

The command you were trying to run (eg rclone copy /tmp remote:tmp)

rclone sync koofr:RCE hidrive:users/xxxx/RCE --fast-list --create-empty-src-diulti-thread-streams 4 --multi-thread-cutoff 64M --retries 3 --low-level-retries 10 --checksum --stats 5s --progress

Please run 'rclone config redacted' and share the full output. If you get command not found, please make sure to update rclone.

[hidrive]
type = hidrive
token = XXX

[koofr]
type = koofr
provider = koofr
user = XXX
password = XXX