Speed display problem

Hello friends,
When I start the car, I think there is a hum from ten consoles. Like the supurge sound you heard from afar. There was that voice since morning. When I pressed the gas, there was a noise, and my foot was making noise when I took it off the gas. After a 50 km drive, the engine light came on and the speed hands fell momentarily and came back again. If I were going in 90, it was falling 70e. When it was 80, it was falling 70e. In my case, it was falling in half when it was in the warehouse but after 2 seconds it was sitting back. There was no problem with the vehicle's departure. Why might it be caused? Has anyone experienced such a situation before?

have the battery and charger checked.

I had the same problem and it was fixed when the battery was changed.