The $300,000 Rivals tournament most likely refers to the Unrivaled “Crown the One” 1v1 event, and the champion earned $200,000 from the prize pool. The source available here confirms the prize structure, but not the winner’s name.

What’s confirmed

  • Total prize pool: $300,000.
  • Champion prize: $200,000.
  • Runner-up prize: $50,000.

What’s missing

  • The available result does not identify who actually won the tournament.

Possible ambiguity

There are also other “Rivals” events with a $300k prize pool, including Twitch Rivals/Bloxfest and a Marvel Rivals creator championship, so the exact winner depends on which tournament you mean.

TL;DR: I can confirm the $300,000 prize pool, but not the winner from the information available here.