Jason predicted on June 20, 2020 that Joe Biden would win the November 2020 U.S. presidential election and that Donald Trump had effectively lost his ability to win.

This is correct as to the main, testable claim:

• Joe Biden won the 2020 U.S. presidential election, securing 306 electoral votes to Donald Trump’s 232. Major news organizations projected Biden as the winner on November 7, 2020, and Congress certified the Electoral College results on January 7, 2021.
• Sources such as the official Electoral College results and major news outlets (e.g., Associated Press, New York Times, BBC) all confirm Biden’s victory and Trump’s loss.

The causal explanation Jason offered (that Trump lost because of mishandling COVID-19 masks/leadership and the response to social unrest) is harder to test directly, but the binary outcome that Biden wins / Trump loses is fully and clearly verified by the election results. Therefore, the prediction is evaluated as right on its central, falsifiable claim.