@FunctionDJ i guess you updated restic but did not make a new backup. This new feature works fine with 0.17.3, albeit that all backups made with prior versions <17.0 will show no data in the size column as there is no data stored in the repository.
Going back to the original question, one can also achieve snapshot size information (“how much storage my snapshots are taking”) if you set up metrics monitoring. For example with Prometheus and a Grafana dashboard.
There are various tools who can help with that, including rest-server. Some solutions are already discussed on this forum:
Then you can get something like this example, the npbackup dashboard:
p.s. Also metrics monitoring will not generate/show data for backups made in the past.