If you thought there was no way to really resolve the endless time loop in Happy Death Day 2U, then congratulations: You understand the concept of movie franchises.
The following post about Happy Death Day 2U credits scenes contains SPOILERS.
Yes, while HDD2U gives its intrepid hero Treedays, her story continues after the closing credits — setting up several possibilities for a Happy Death Day 3.
Having learned a lot about algorithms while she was trapped in the time loop, Tree offers to help.