External monitor locks at 30fps while playing games in fullscreen mode.

[Tej2]

I just bought a new acer VG240Y M3 monitor which supports 180hz, firstly I cant see the option to set my refresh rate to 180hz in the display settings so I can only set it to 120hz. Second, when I play games (Eg: Valorant) on fullscreen mode the monitor locks to 30fps, it is only when I play it in fullscreen mode that my monitor does this, when I change it to fullscreen-windowed mode I get proper 120fps. The monitor switches on and off like its getting a new input and just locks to 30fps on fullscreen mode. Only while playing games on fullscreen mode I experience this issue, all the other times the monitor works like its supposed to. Can someone please help me regarding this?

I've attached  Intel-System-Support-Utility log with this post for your reference. 

Thanks.

[MUC]

Acer Nitro VG240Y M3 Widescreen Gaming LED Monitor

1920 × 1080 @ 180 Hz

1 x HDMI 2.0

1 x DisplayPort 1.2

Dell Inspiron 5590 Setup and Specifications

1 x HDMI 1.4b

1 x USB-C with DisplayPort 1.2

Please connect your laptop with one of these cables to the DisplayPort connector of the monitor:

• Zeskit MAYA 8K Bi-Directional USB-C to DisplayPort 1.4 Cable
• Club 3D USB Type C Cable to DP 1.4 (CAC-1557)
• Cable Matters USB-C to DisplayPort Cable - 8K Ready (201036)
• Cable Matters Premium Braided USB C to DisplayPort 1.4 Cable (201336)