This is because HP has installed a CH keyboard in the new compact layout on the OmniBook Ultra Flip 14-fh0522nz.
The < > and \ keys are no longer to the left of the Y key as usual, but have been moved to L as secondary functions.
How to reach them:
- Fn + L = < (you've already found it)
- Fn + Shift + L = >
- Fn + Alt Gr + L = \
If that doesn't work: In Windows, under Change keyboard layout, you can activate German (Switzerland) or German (Germany) on a trial basis and see which layout fits better.