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Progress points required to open the Vault has changed from 900 to 1000
Update:
According to u/WotC_Jay:
The vault has been 1000 points to open since mid-2018. The website had the wrong value on it (900), so we updated the website. Nothing has actually changed in-game. No one should have lost any progress; if you feel like you did please contact CS and we’ll look into it.
My original post:
According to everything I've read online (articles, blog posts, etc.), the Vault opens after 900 progress points, where each fifth common gives 1 point and each fifth uncommon gives 3 points. This is confirmed by using the Internet Archive Wayback Machine to look at a snapshot of the official Wizards website on rarity and drop rates from June 19, 2019:
https://web.archive.org/web/20190619221143/https://magic.wizards.com/en/promotions/drop-rates
However, according to the live version of that same website, the vault now requires 1000 progress points to open:
Wizards Jay
The vault has been 1000 points to open since mid-2018. The website had the wrong value on it (900), so we updated the website. Nothing has actually changed in-game. No one should have lost any progress; if you feel like you did please contact CS and we’ll look into it.