Can I buy AppleCare+ now and get battery replacement covered at 79% health?

I have a MacBook Air 13" and my battery health is currently at 79% with “Service Recommended” showing in System Report. Cycle count is around 769, so it’s under 1000 cycles.

Apple is offering AppleCare+ and it says battery service is covered if the battery is under 80%. My question is: if I buy AppleCare+ now, will Apple cover the battery replacement immediately, or could they deny it because the battery issue already existed before I bought AppleCare+?