ls (and du) block size specification with thousands separator fails

I just upgraded to Ubuntu 25.10 and got an error with ls:

% /bin/ls --version
/bin/ls (uutils coreutils) 0.2.2
% /bin/ls -l --block-size="1"
total 12288
drwxr-xr-x 22 user user 4096 Oct 26 09:18 documents
drwx------  3 user user 4096 May  2 21:56 snap
drwxr-xr-x  9 user user 4096 Oct 27 11:33 temp
lrwxrwxrwx  1 user user   14 Oct  2 23:05 tmp -> /run/user/1000
% /bin/ls -l --block-size="'1"
bin/ls: invalid --block-size argument ''1'
% printf "%'d\n" 4096
4,096

According to https://www.gnu.org/software/coreutils/manual/html_node/Block-size.html, the leading quote should add a thousands separator. It's possible that this was being silently ignored before the upgrade and I never noticed, but now it's throwing an error. I have LC_NUMERIC=en_US.UTF-8 and the last printf command shows that's in effect.

du suffers the same, though df appears to work as intended.

Reproduce the issue with ls and du using --block-size="'1" and LC_NUMERIC=en_US.UTF-8, then compare the behavior with df and GNU coreutils. Trace the command-line block-size parsing and numeric formatting entry points for these utilities. Done means the leading quote is accepted and thousands separators are applied consistently without breaking existing block-size values.