Some say Jerome’s Latin wasn’t all that hot and that might be so but it is sure easy to read.
My understanding was that the church fathers believed that the latin should be not as complicated as the classical, or more ancient, latin. A simpler latin was preferred because the scriptures themselves were “simple”. The claim that the medieval fathers weren’t very good with latin was all based in a misplaced educated snobbery of those who accused them, frankly.
At least, that was what I learned about it. Others may know more.