Understanding Retention Report Criteria and Cohort Qualification Dates

I set my Retention report with the criteria On or After Each Month. Why is the cohort Dec 1, 2024 retention in column <1 Month shows that "Profile will continue to qualify until the end if Jan 30"? Shouldn't it stop counting before the end of Dec 2024? the cohort Dec 1, 2024 retention in column Month 1 also shows that "Profile will continue to qualify until the end if Mar 1". Why not Dec 31? How does this work?