The workflow that I posted is about light leaks caused by incorrect shadow maps. If you turn off “Screen Space Reflection” and “Free Lighting Cache”. Do you still see the white line artifacts? Is better if you post the problem scene.
For dealing with the limitation and artifacts of screen space reflection since it can only use reflection of what is visible in 2d space. Is probably better to start another thread about solving these problems. To have screen space reflection work correctly for floors and walls you may need to add reflection probes. See my solution in this thread Eevee Reflection Clipping.