Dual boot TW/Win11

Hi, every once in a while I have boot issues with my dual boot laptop where Windows 11 and Tumbleweed are installed. Just today I booted Windows (which does not happen very often but sometimes I need to) and had to install a bunch of updates. Now I cannot boot to TW anymore. So something must have destroyed the boot. When I open the BIOS during boot I still have the entry opensuse-secureboot available but selecting it just brings me back to the same selection so apparently something is broken there. What is the correct way to recover that and can I avoid this somehow? Thanks, Wolfgang