Other articles I have been reading on the topic do mention it:
Unity has also clarified the changes are "not retroactive or perpetual", noting it will only "charge once for a new install" made after 1st January 2024. However, while it won't be charging for previously made installs, fees do indeed apply to all games currently on the market, meaning should any existing player of an older game that exceeds Unity's various thresholds decide to re-install it after 1st January, a charge will still be made.
When I say that it applies retroactively, I mean that it applies to games released in the past.
It's true that they are not retroactively charging devs for past downloads. That would have been even worse.