The log shows that restic spends a long time with reading hundreds of lock files. I’m kinda surprised that restic list locks did not list those. Can you run restic list --no-lock locks again and check how many lock file names it reports (the --no-lock option should speed up the command a lot)?
You should be able to remove these old lock files with restic unlock. If that doesn’t help then try restic unlock --remove-all, but make sure that no other restic instance is running in parallel.