Using the Microsoft EES of our Univ., you may have uploaded files to Teams/OneDrive, carelessly setting them sharable to all the Univ. members.
Otherwise you await, we recommend to share them only to your private groups.
For details, please reference https://www.cc.tsukuba.ac.jp/wp_e/wp-content/uploads/MSFiles20210610_e.pdf

For detail, please reference “Change in the location where to store recordings of Teams meetings“.