So i decided to do the fortify restoration/alchemy loop to make 400% enchanting and smithing potions.

After using a 400% smithing potion and sharpened a bow, i keep improving weapons at broken numbers like 500 and 600 even though i have no fortify equipment on or potions
Is it a glitch or a locked value ir something?
I would revert to an older save but it still seems to have the same problem.
Is there a way to fix this?