Any electronic device, regardless of manufacturer, can suffer a failure out-of-warranty. Most users experience many years of trouble-free use from their iPad.
The appearance of bright patches are often attributable to partial delamination of the screen backlight diffuser, some models (such as the iPad Pro 10.5 and closely related third generation iPad Air) being more susceptible to this problem than others. All conventional laminated LCD displays can suffer this type of issue.
Faults or defects discovered within the warranty period are usually resolved by Apple without quibble. If you have benefit of an active AppleCare+ plan, again the problem will usually be addressed by way of a replacement/exchange device; being an insurance product, there will be small excess/deductible fee to pay. Outside of warranty and AppleCare plans, repairs are chargeable at Apple's standard terms and costs:
iPad Repair and Service - Apple Support
In many countries, the Apple’s limited warranty is one year. However, you should also note that in addition to the manufacturer’s warranty, in many countries you will also have statutory rights with the retailer - which may exceed those of the limited warranty offered by the manufacturer. For example, with member states of the European Union, the manufacturers warranty is extended to at least two years; within the United Kingdom, defects may be covered for up to six years from date of purchase.
In summary, Apple’s limited warranty is only part of the equation. In general, your first port-of-call should be with your retailer - which may not necessarily be Apple.