I’ve got no reason to believe that the odds of getting roots has changed. (But no proof that it hasn’t.)
I will say that given that the odds of any 3* crafting items are quite low, so a long burst of exceptionally high or low return should hit many players.
Personally, I farm AR in the 3-flag zone for best overall farming and best total return of 3* and 4* crafting mats even tho specific crafting mats like roots or nuggets have higher yields elsewhere … but I’m farming for backpacks too, so I’m not sacrificing anything.