“We’ve addressed the issues that caused display flickering and yellow tint. Customers concerned that their iMac is affected should contact AppleCare.”
If you think you have these issues with your iMac then contact your Mac store repair center as soon as possible. Here are some websites for the ones in Saudi Arabia: Itechia, Al-Arabiah and Arab Computers.
Arabic version of this post on SaudiMac.net.