It means visa numbers are available for applications with priority dates of September 8, 2020 and earlier. It does not affect the I-130 approval process. It means approved I-130s will sit at NVC until a visa number is available.
My understanding is that I-485 / F2A remains current through at least April 30, 2023. See https://www.visajourney.com/forums/topic/797957-april-visa-bulletin-released-with-f2a-eb2-eb4-retrogression/?do=findComment&comment=10819165 for my reasoning.
But keep in mind USCIS can change this in a later month to the other chart. Or the state department can retrogress both charts in a later month.
Normally F2A is not current. It went current several years ago.
While I do not know why it stayed current for so long, it was inevitable that it would stop being current.
bunbuni reacted to Crazy Cat in F2A Visa Bulletin