The timings are very similar for the second weekend of the Battlefield 6 beta. It opens at 9am British time on Thursday, August 14 and closes at 9am on Monday, August 18. An initial early access version kicked-off yesterday (August 7) at 9am British time. However, that was only open to the players who met the following conditions:

Battlefield 6's open beta isn't open to all players yet, but it's already attracted hundreds of thousands, if not millions, of players.