It looked a bit odd. I’d have thought the tiles that were once farmland would be fully converted to road.
I can’t speak for the current build - because back in the day I quickly learned crops do not grow on a road (or anything else for that matter!), and have never tried to farm a road since.
Did you build the road after or during the farm plot creation?
And is the farm genuinely producing crops from the roaded-over tiles, or is just a visual effect? (it might be hard to tell the former if your road is only covering a small proportion of the tiles for that particular field)
I zoned the farm after the road was built. It allowed me to zone across the road, and I presumed it would simply exclude the road tiles from growing anything or being farmed. I can’t tell if they are genuinely producing crops or not.