From Game Revolution: “A brand-new Rocket League update is available to download and install across the PS4, Xbox One, PC, and Nintendo Switch versions of the game right now. Primarily, the update is adding in the Rocket League Radical Summer Phase 2 content, but there is a little more to the Rocket League 1.65 update that just that, however. Skip to the end of this guide to read through the complete list of Rocket League 1.65 update patch notes. If youd rather spend a little more time reading through the new Rocket League update changes, however, you can do so below. Whatever the case, itll certainly be calculated.”
Source: N4G PC Rocket League Patch Notes v1.65 Update Released