MacBook Pro not recognising 4k

I have a MacBook Pro 2019. It worked perfectly normal for a year with the usb c cable that came with it.

Suddenly, the monitor just changed resolution and Mac doesn’t recognize the full resolution.

Things I’ve tried:

• Bough a new Thunderbolt 3 cable.
• Updating ios
• Restarting monitor default settings
• connecting via HDMI - it recognizes 4K but only 30hz and it’s flickering
• connecting a different MacBook I think it’s 2018.

What I’ve noticed is that:

• For some reason my Xbox works fine with the monitor via HDMI. No flickering and full scale resolution.

[Re-Titled by Moderator]