Most likely the PlatformIO VSCode extension auto-updated (and triggered the PlatformIO core to update also). Which is the main reason you need to restart VSCode (so that the extension can reload). If you had bad internet, you probably want to turn VSCode’s extension auto-update off, and also PlatformIOs, and manage updates manually.
The PlatformIO core (“PlatformIO CLI”) does have an update check interval, which is by default every three days, but I think that is only used to show a notice that a new version is out, and doesn’t update on it’s own. You can see this if you run pio settings get from a PlatformIO terminal in VSCode, and change the value using pio settings set check_platformio_interval new-value