Through proton, yes. The game has always worked with anti-cheat disabled (so no PvP multiplayer), but proton-compatible anti-cheat has been supported since early April, so all multiplayer functionality has worked since then.
This article is referring to a recent MCC patch that broke proton anti-cheat for about a week, thankfully it's fixed now.
Element isn't perfect, but what's a better alternative? A giant Signal group would be a horrible idea, since everyone's phone numbers would be exposed to the other members (plus there's a 150 group member limit), and Discord is obviously much worse than Element (from a privacy perspective).