Because it was taking care of a continuous D2R Items connection requests from servers for games. While we were at it, we also noticed that we could modify our configuration to improve our database event logging. This is essential to return a stable state in the case an issue with the database, and therefore, we made those improvements and undertook further analysis of the root cause.
It's not exactly the recipe to have an enjoyable weekend, but that's what it was. It also explains why players had so many issues with progression, too. You'd choose your character, start a game and then play for some time, but the regional server couldn't communicate with the central database due to an incident.
The game couldn't reveal what Diablo 2's "ground truth" about the brand new gear and XP you'd gained, resulting in frustrated players losing some of the progress they'd made.
The problem got even worse from there. In the end, the Diablo 2 servers came back up and running, but they came back online at a time when most players were online--so even though the servers recovered quickly, they crashed almost instantly as soon as hundreds of thousands of Diablo 2 Resurrected Items instances fired up.