TWAP is the average of daily closes over the trailing 200 weeks, every trading day weighted equally, taken over every bar Yahoo Finance holds for the equity rather than only since 2020. Premium versus TWAP measures whether the equity is trading above or below that time-weighted cost basis. Gravity Risk is that premium clipped at the 1st and 99th percentile of its own history, so that once a stock has about 100 trading days behind it no single flash wick sets the scale, then rescaled to 0-100 and grouped into levels 1-10. It is banded on the homepage's cut points: accumulation below 25, mid-range 25 to 50, late-cycle 50 to 75, and the stretch that has marked tops at 75 and above. It is the same figure the Gravity Profile page shows.
The pink line is the volume-weighted average price since Dec 2020: each day's typical price, (high + low + close) / 3, weighted by the shares traded that day. TWAP counts every day equally; VWAP counts every share equally, so it is the average price paid per share traded since Dec 2020. Price above the line means a share bought at that average is in profit today, below it at a loss. The line is drawn for context: the Gravity levels on this chart are still computed from the TWAP premium alone.