List of steps to reproduce (step by step, including full links if applicable):

Use the visual mode to make a link to this URL: https://en.wikipedia.org/wiki/Wikipedia_talk:Spam/Archive_5#%22The_current_consensus_on_Wikipedia_is_that_[...]_anonymous_solicitation_[is]_inappropriate.%22

What happens?:

Diff. Notice that the resulting wikitext is broken (probably because it doesn't percent-encode the square brackets). In fact, if you actively produce a percent-encoded URL and try to link to that, it "fixes" the percent-encoding to break the resulting link again.

What should have happened instead?:

It should make a viable, non-broken link.