WASM: Cannot cut the text using keyboard shortcut on Firefox

Steps to reproduce:

1. Build and run any text example on Firefox browser, e.g.:: https://doc.qt.io/qt-6/qtwidgets-tutorials-notepad-example.html
2. Type any text, select it and press Cmx+X or Ctrl+X on Windows/Linux

Expected: Text could be cut out

Actual: Nothing happens.

Reproducibility:  100% 

NOTES: It works well in Chrome.