I recently upgraded to Fedora 34 (beta) and installed the Brother drivers for MFC-5895CW.  The printer worked.  The scanner did not.

'scanimage -L' could not find the scanner.  The device is attached via Ethernet, and configured by IP.

I did not detect an error during install.

While researching the problem I found an error running the following command:
SANE_DEBUG_DLL=255 SANE_DEBUG_SANEI_TCP=255 scanimage -L &> scanimage.debug


Steps to Reproduce:
1. Install Brother drivers for printer and scanner (version 3)
2. Run scanimage -L

Result: nothing found
Expected: Brother found

Error:
[20:21:36.603691] [dll] load: searching backend `brother3' in `/usr/lib64/sane'
[20:21:36.603697] [dll] load: trying to load `/usr/lib64/sane/libsane-brother3.so.1'
[20:21:36.603707] [dll] load: dlopen()ing `/usr/lib64/sane/libsane-brother3.so.1'
[20:21:36.603825] [dll] load: dlopen() failed (libusb-0.1.so.4: cannot open shared object file: No such file or directory)

After running 'dnf install libusb' simple-scan was able to find the scanner.
*Problem solved*

Results After:
20:29:44.058269] [dll] load: searching backend `brother3' in `/usr/lib64/sane'
[20:29:44.058275] [dll] load: trying to load `/usr/lib64/sane/libsane-brother3.so.1'
[20:29:44.058285] [dll] load: dlopen()ing `/usr/lib64/sane/libsane-brother3.so.1'
[20:29:44.058437] [dll] init: initializing backend `brother3'
[20:29:44.061870] [dll] init: backend `brother3' is version 1.0.1


I'm not sure if this is a Fedora issue or something Brother wants to handle in the install script. I did not create a bug with Brother, but did leave them a similar message on their driver site.

Is libusb something that should be installed by default?


This bug led me to the solution.
Reference: https://bugzilla.redhat.com/show_bug.cgi?id=1564763 

Thanks for a great product.