Apple is still going ahead with this regardless. My understanding the rollout was delayed because of ongoing financial hardship on everyone in the world because of COVID (and to give more time to advertisers, developers and others to prepare).

Mozilla is also asking everyone to publicly support Apple's decision because it's good for consumers, which in result would also force others to also adopt it (Android), but also because on the other end of this decision are advertisers, game developers and Facebook that are publicly telling everyone it's a bad thing since it'll hit their wallets.