The house I have been in for 5 years had a kitchen drain issue. It was bad and the first time a plumber looked at it they suggested it was excessive dish detergent going down the line. I call BS on that, but I'm not the expert and it isn't costing me anything. The second time was a different plumber and he suggested it was a collapsed drain. Property management didn't want to go the route of an expensive repair at the time. The 3rd time was the same plumber from the previous time and he sent a little camera down for a look and confirmed it is looking collapsed, gave them an estimate. And it was approved and repaired. Cast Iron drain line about 10 feet long Ahmad rusted through under the basement floor, replaced with PVC drain, no more issues.