Based on the search results, there are conflicting reports about what happened to Roblox on October 21, 2023. Some sources claim that Roblox was shut down on that day, while others report that the platform experienced server issues and was down for a period of time.

According to the sources that report server issues, Roblox was experiencing the "503 Service Unavailable" error message, which prevented users from accessing the platform. The cause of the error is unclear, but some speculate that it was due to an influx of players, possibly related to a major update to one of the most popular games on the platform.

It is worth noting that some users were able to connect to Roblox during the reported outage, while others were not. The official Roblox status page cited "degraded performance" and stated that the issue was being investigated.

In summary, there are conflicting reports about what happened to Roblox on October 21, 2023. While some sources claim that the platform was shut down, others report that it experienced server issues and was down for a period of time.