Hi, you are receiving the 'low visitors' warning. This means that WordPress is not being loaded into memory at a regular enough interval. This means that the backup is not able to resume on time.
We have a guide available that explains the issue further, and provides some suggestions for resolving the issue (e.g. through scheduling some dummy visits to the site):
https://updraftplus.com/faqs/why-am-i-getting-warnings-about-my-site-not-having-enough-visitors/