Honestly, I wouldn't have been able to tell you this two weeks ago. I know all this now because completions in a language I don't normally use felt off somehow, and figuring out the solution involved going deep on how Emacs handles completions. That ended up not being relevant to the root cause, which was a change in Doom causing snippets to be overvalued in LSP completion, but at least I know a lot more about vanilla completion methods now!