Mastodon isn't and has never been "a less toxic social media platform than Twitter". Touting it as one or even just having such a notion of it being one is inherently fallacious, because toxicity is not linked to platforms; it is linked to people. Because Mastodon is not a single entity, absolutely no control can be exerted beyond the instance one owns / one is on, so as the user base grows, the toxicity will only increase in a rate faster than Twitter does. That is not something preventable unless Mastodon goes full proprietary and walled-garden.
Every time I see a post about how Mastodon did not meet the author's expectation of a non-toxic social media, I am tempted to send this to them but then I realize it makes no sense if someone already leaves. I think Mastodon people should instead stop selling Mastodon as a single entity or a "less toxic" place because that is not an expectation Mastodon will ever be able to fully meet.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!