This is not an ad nor endorsement ... just saw info on this and thought it worth sharing.
Unicheck
Moodle is listed as one of the LMS's
"Integrations with LMSs
We love LMSs as much as you do. That’s why Unicheck supports LTI, API,and plugin integrations. It is equally good for a faculty and entire university use.
Unlimited File Storage
We know you have lots of them. Storing countless student assignmentsand reports is no longer problematic. No restrictions. Export them if you need. "
https://unicheck.com/
https://unicheck.com/plagiarism-checker-google-docs-students
'spirit of sharing', Ken