When a path of a share is not accessible to smbd for some reason, the message is:
[2021/04/22 19:56:10.962390, 0] ../../source3/smbd/service.c:781(make_connection_snum)
make_connection_snum: canonicalize_connect_path failed for service transmission, path /data/some_share
This does not point to a specific reason and is hard to interpret (you can find it asked on the internet multiple times with no clear explanation besides "disable selinux").
The issue turns out to be caused by failure to traverse the higher paths, even if the full path would be allowed.
601954 lstat("/data", 0x7ffcabcad570) = -1 EACCES (Permission denied)
A better log message with the specific failure would make this much easier to debug: for example what errno happened and when accessing which path.