Ubisoft initially stated that The Division 2 open beta would run from 01 to 04 March 2019, then announced a 24-hour extension and finally corrected themselves, saying that it was always the intention to keep the beta running until 05 March.
The Division 2 open beta test was to kick off on 01 March and conclude on 04 March 2019. It is quite possible that the players simply gave up trying to log in after the supposed expiry time but Ubisoft announced it would go on until 05 March 2019 in a now-deleted tweet.
It was quickly on the official The Division subreddit and the reason for the tweet's deletion may have been partially explained. According to Ubi-Johan, the Community Manager assigned to The Division games, this is not actually an extension and the plan was always to have open beta until 05 March 2019 and it will end at 10:00 AM CET / 01:00 AM PDT.
This may have been an issue in Ubisoft's initial communication as they clearly stated the beta would end on 04 March 2019, which could lead to players and apparently even some Ubisoft employees into believing this was a 24-hour extension.
Either way, open beta participants will be able to play about 24 hours longer than they initially thought, just in case there are some bits of content they didn't get to explore just yet.
On the flip side, progress made during the beta tests, regardless of whether it was open beta or private beta, will not carry over to the main game once it launches on 15 March 2019. Still, it is a good opportunity to test out the weapon balancing changes or go searching for gear chests around Washington DC to get a better sense of where Massive Entertainment usually place them.
The Division 2's beta tests have proven to be superior to the game's competitors so far. It's not in a perfect state but open beta fixed many issues private beta had, which wasn't an unplayable mess to begin with. None of the betas hard crashed any PlayStation 4 systems so far.