I agree with you and do consider the default l glyph to be a poor choice, insufficiently distinct from 1. Fortunately, the Code variant of the font goes for a curved tail on l, so that it’s sufficiently distinct.
(However, if you try to enable both the Code and Poly features—Poly meaning “don’t be a true monospace, make characters like l and i a little narrower and characters like m a little wider”—you end up with a slightly narrower flat-bottomed l glyph, rather than a curved tail. See this, for example, in https://chrismorgan.info/blog/make-and-git-diff-test-harness..., which is set in Code + Poly. Disable the `code { font-feature-settings: "ss01" 1, "ss02" }` CSS rule to see the effect of removing Poly—you get the curved tail l glyph back again. I’ve been meaning to sort out a better glyph for the combination, but I haven’t gotten round to it yet, because it’s annoyingly difficult to actually do that sort of thing.)
(However, if you try to enable both the Code and Poly features—Poly meaning “don’t be a true monospace, make characters like l and i a little narrower and characters like m a little wider”—you end up with a slightly narrower flat-bottomed l glyph, rather than a curved tail. See this, for example, in https://chrismorgan.info/blog/make-and-git-diff-test-harness..., which is set in Code + Poly. Disable the `code { font-feature-settings: "ss01" 1, "ss02" }` CSS rule to see the effect of removing Poly—you get the curved tail l glyph back again. I’ve been meaning to sort out a better glyph for the combination, but I haven’t gotten round to it yet, because it’s annoyingly difficult to actually do that sort of thing.)