There's a lot of factors in play:

User scope only covers a maximum of 90 days no matter what. Beyond that, it'll count as a new user. The cohort analysis covers 1 Month intervals. If you're not stitching sessions (see extended privacy agreement check in your Admin panel) then Google won't be able to tell you when a session comes from the same User.

With all that in mind, the stats you're looking at in Cohorts are Users alone. The second is showing Sessions initiated by Users.

If you had 10 users, all started 2 sessions each in the first month, you'd see 0% on the 1 month Cohort. But 50/50 on the returning user sessions. Now 1 of those users came back after 1 month. You'll now get higher returning stats (52/48) and 10% on the 1 month cohort. The stats you're showing mean that a larger number of users are using the site a few times in the first month then leaving.