This is actually working as intended; In 1.14 all paths were changed to Grass Paths, Planks, or sandstone. If you look into the code you'll realize that all references to gravel paths as well as the gravel paths themselves are gone
Anybody doubting whether it's intentional or not should seriously see this video from slicedlime where he talks about the new village generation in 1.14 and how streets are made from grass paths or planks on water etc. https://youtu.be/b6eBndQ_jK0
@Anthony Cicinelli You can find the proof in the code, but I doubt Mojang or anyone sane would appreciate me putting 10 thousand or so lines of code in this one thread. However, as someone else here has said, the new JigSaw system only uses Sandstone, Wood Planks, and Grass Paths as roads for Villages now, Gravel has been totally removed as a path type
It doesn't matter that it's been many years, it's not my fault they're taking so long to do something, that doesn't change the fact that this issue is still an issue in the game, a wrong one.
I’m not sure if this is intentional or not. It might be due to
The code was changed to not make paths on sand turn to gravel
This was changed for Bedrock parity
Also, sandstone paths do not turn to regular paths when on grass.