When you start with systemd Kibana runs as the Kibana user, so if somewhere along the line you started manually or created that directory with another user like root , Kibana may not be able to access that directory.
The location of the data files written to disk by Kibana and its plugins /var/lib/kibanapath.data
sbrown@stephenb-metrics-test-es1:/usr/share$ sudo ls -la /var/lib/kibana
drwxr-s--- 4 kibana kibana 4096 Oct 23 2021 .
drwxr-xr-x 41 root root 4096 Oct 26 2021 ..
drwxr-xr-x 4 kibana kibana 4096 May 10 2020 headless_shell-linux
-rw-r--r-- 1 kibana kibana 178 Aug 16 2021 kibana.keystore.bak
drwxr-xr-x 2 kibana kibana 4096 May 10 2020 optimize
-rw-r--r-- 1 kibana kibana 36 May 10 2020 uuid
Note the permissions / users, why your install is looking / trying to put data in the usr/share/kibana directory I am unclear. But the error makes a bit sense ... when started with systemd Kibana runs as the kibana user so it would not have permissions to read and write in the /usr/share/kibana directory.