"What your situation is the 401K plan administrator probably thought you were rolling the funds from the 401K to a traditional IRA hense the code G."
No, the 401(k) plan administrator understood that this was a direct rollover to a Roth IRA, hence the correct taxable amount in box 2a. Code G is used for all direct rollovers from a traditional 401(k) account, including those to the designated Roth account in the same plan or to a Roth IRA.
