Why is a trader’s PnL here different from the figure I saw elsewhere?
Because it measures something different, not because either figure is wrong.
PredCheck counts only short-term crypto markets — the 5m, 15m, 1h and 4h Up or Down markets on supported assets. Anything a trader did in sports, politics, equities or longer-dated crypto markets is excluded entirely, so a trader active across the whole venue will show a smaller figure here.
The bigger difference is that Trade PnL is net of costs. A headline profit figure is usually gross — it counts what a trader won and ignores what the trading cost them. PredCheck rebuilds the result from raw fills and subtracts the fee each market’s published schedule implies for every one of them. On a 5-minute market a round can pay up to $1.75 per 100 shares, which at even odds is 3.5% of its own volume. For someone trading a hundred rounds a day that is not a rounding difference; it is frequently the whole result.
What Trade PnL does not do is add the venue’s rebates and rewards back in, because those are paid to an account rather than to a market. That sum is published as a second figure, Overall PnL, which is what the account took home and the one to compare against the venue’s own profile page.