You are not alone with this issue. I picked up a 2020 Forte FE about 3 months ago, it happens about 1 to 2 times a week. The only time it happens to me is on my drive to work at around 0530 when it is still dark out. A few times it happened while on the interstate and a couple of times at a dead stop. One stop was at a light, behind another car and the other time was when I was at the chain link gate of the place I work. I took it to the dealer, they tested the system and said it was working normally. They opened a ticket with TechLine, whatever that means, and I have not heard anything since. This last week I had it pop on 3 times, Wednesday, Thursday, and Friday. I talked to the dealer again, gave them even more information and they are going to see if they can find anything out this week. If I hear anything back, I will share what I find here.
I did notice that the LKA was still working normally on mine when the error popped up on the dash. I saw the indicator was green with the steering wheel lit up too, so I tested it and drifted over to the center line, the wheel bumped back to the center of the lane as it should.
I love the car, it is a manual, it gets amazing gas mileage, looks really good, comfortable, but this issue is really damn annoying. I told the service advisor at my dealer to tell TechLine to either fix it or remove it. The only time that I would like the system to be functional, early in the morning while it is still dark, it seems to fail the most. Not exactly a "safety" system I would put much stock into.