iPhone 17 Pro screen looks dim and yellowish

You can’t set the screen brightness slider the same for screens that have different maximum brightness levels. The scale is different.

If you feel you’re having screen brightness issues after doing forced restart you need to have Apple perform diagnostics on your iPhone. It can be done in person at an Apple Retail Store or at an Apple Authorized Service Provider. You can also contact Apple Support and request remote diagnostics.

If you’re in the US, please call  1-800-MY-APPLE, or outside the US, consult the support articles below. In Canada, call 1-800-263-3394.

Contact Apple for support and service - Apple Support

Genius Bar Reservation and Apple Support Options - Apple

Explore Service Locations

Try doing a forced restart, that resolves many screen related issues.

Force restart iPhone - Apple Support

josueperalta wrote:

I did that and it didn’t work. I placed both devices side by side with the same brightness level, and iPhone 17 Pro still looks dim compared to 14 Pro. What else can I try?

Jeff Donald is right. You can't set two different model iPhones to the same setting to compare brightness. I'd be willing to bet if you set the brightness on your 17 Pro to maximum brightness and your 14 Pro to Maximum brightness and go outside in the sunlight, you'll likely see how much brighter your 17 Pro with a peak brightness of 3000 nits is compare to your 14 Pro.