https://wccftech.com/2020-27-inch-imac-ram-upgrade-expensive-third-party-solutions-cheap/

Apple didn’t change the way it charged customers for component upgrades when it officially launched its 2020 27-inch iMac. Sadly, it doesn’t look like the company is going to be changing its stance on such upgrades for the foreseeable future. However, if this was the 16-inch MacBook Pro, then you’d be out of luck because everything is soldered to the motherboard. With the 2020 iMac, you have the option to upgrade the RAM yourself in case you find Apple’s upgrade options a bit too pricey.

Yes, you read that correctly; Apple will charge you a jaw-dropping $2,600 to upgrade the RAM on your brand new, shiny 2020 27-inch iMac. The price that Apple slaps on this upgrade is actually more than the cost of a new 27-inch iMac but thankfully, there is a way to upgrade the existing RAM on this AIO. There is a backdoor that gives the user access to the RAM so they can swap out the existing parts for a completely new kit just in case they require this much memory.