Presumably you have an iPad Pro 12.9" with a Liquid Retina XDR display.
About the Liquid Retina XDR display on iPad Pro – Apple Support
This model iPad uses a miniLED array backlight. As illustrated in your photo, you appear to have a partial failure of the backlight. The only remedy for this fault is replacement of the iPad screen assembly.
For practical purposes, in lieu of repairing and returning your own iPad, Apple usually exchange the iPad for a renewed/refurbished iPad of the same model and specification. The cost of the exchange is the same as would otherwise be charged for repair. Unless you have benefit of an active AppleCare plan, an out-of-warranty repair while expensive will be somewhat less than the cost of a replacement iPad.
As for out-of-warranty repair costs, Apple offers a fixed-price price repair. You can verify eligibility and cost for your region/country here:
iPad Repair & Service - Apple Support
If you have an active AppleCare+ plan, the cost of repair is reduced to a small excess/deductible fee.