Hi Ruta, I've checked the RAF in Capture One and you can see it shows the focus plain of the image painted in green.
So, as Jerryy pointed out it's a very thin DOF that makes the most part of the image unsharp. Besides even shooting at F11 or F16 from this perspective you hardly get all-in-focus image. I agree that focus bracketing or focus stacking is the only way to go here.
What about your lens it's perfectly fine. I upload processed file and as you might find the area which is in focus is tuck sharp.
https://drive.google.com/file/d/1MuOChe5snmYV_Fqv13qeMqmN_LeRg5iD/view?usp=sharing