Topic: Question related to monitor resolution and refresh rate.

I just bought a 1440p monitor (X= XRGB27WQ V2 27" IPS 1440p 165Hz FreeSync/G-Sync DP HDMI RGB Gaming Monitor) than can run up to 165hz, which has a 2.0 HDMI port, and I'm using the HDMI cable that came with the PS5. I bought the PS5 back in February. It is however not working well on my PS5. The PS5 display outputs 1440p absolutely fine but the interface is running at 60hz. When hooking up the ps5 to my brother's 1080p 144hz monitor, which has a hdmi 1.4b port, the interface runs at 120hz. The main game I play is rocket league, so I tried it out. The game runs at 120hz but the monitor outputs 1080p so the game looks blurry and it's very unappealing to the eye. The 120hz also looks weird. It is smooth but some things on the screen seem to be running at 120hz while other things seem to not, almost like some weird tearing. I've also tried Fortnite, which is also just running at 1080p 120hz, and again looks blurry. On my brother's monitor, rocket league Fortnite were running perfectly, and I have no idea why this isn't the case for my monitor. Any suggestions? I've searched online but can't find anything related to my issues.