The "Updated" time shown on the projects page doesn't match the last activity time

I occasionally found this problem happened on my Private project created on gitlab.com. The last commit of this project is pushed about 10 months ago in Oct, 2018. But I found that the latest Updated date shown on project page is 7 months ago in Jan, 2019. So I checked the activity history and authentication logs, but there is nothing suspicious, and the project settings seem not be changed either.

Can this be caused by the update of gitlab.com or some issues at that time? I’m a little confused by this. Thanks a lot for your anwsers!