Because the panel is smaller, urls may be cropped more aggressively. We may evaluate small changes to increase the available width for them, so that the user gains some additional browsing context.

I'll do some investigation/experimenting.

Results are not particularly conclusive, but a 5% increase doesn't seem to bring bad consequences.

Discussing with Verdi, another possibility I will investigate next week is to wrap the url to a second row, using the flexible layout.
That requires quite a few dom changes, so I will first experiment in a separate build, validate the approach with Verdi and then see where we're headed.

Spoke with Verdi last week, I'm going to do some experiments with wrapping the url to a second line.

I'm currently investigating this suggestion by Verdi to move urls to a second line when the space is constrained

Let the url wrap, when the screen size is smaller than a threshold (maye be
tweaked in the future). Along with a new proposal by Verdi for the toolbar
overflow behavior, this should allow the urlbar to stay usable in small windows.

Because the title in Quantum Bar should never be empty, a few rules can be
simplified, so they also apply to the url when it's not a sibling of the other
result parts.

https://hg.mozilla.org/mozilla-central/rev/b70e9a9a4486