They literally give you a new slider to increase or reduce the Liquid Glass effect to align with your personal preferences.

Just anecdotally, increasing the blur seems to have an associated performance cost, especially in Springboard ("the home screen".) It's probably only ~100ms for each interaction, so it probably won't impact latency-insensitive users.

As others have said, it helps with the legibility but Liquid Glass is still distracting and illegible. I share the wish that Apple eventually returns to a more sensible, legible UI.

And fixed the dumb sidebar design

Unfortunately the slider does not fix Liquid Glass. Notifications are still unreadable even when you go full opaque. You need to also toggle Reduce Transparency to actually get the UI to be opaque enough to be readable.