Late-night "Today" counts the same day Robinhood does
After 8 PM the broker starts the next trading day, but the dashboard kept measuring "today" from the day before, so a quiet down day was blended into the overnight move and the figure came out far below the broker's.
Today now starts over at the same time the broker's does, and uses the most recent after-hours or overnight price rather than an older one.
Between the close and 8 PM it still covers the whole day, matching the broker.
Stonk Bot