For a Roth conversion from a traditional IRA, this Form 1099-R will have either code 1, 2 or code 7 (not code G) depending on your wife's age and how the rollover was done.
I can't imagine any likely circumstances where this would be entirely nontaxable. If your wife made a nondeductible traditional IRA contribution for 2019, make sure that the traditional IRA contribution has been entered. The taxable amount of the Roth conversion is calculated on Form 8606. If your wife had other money in traditional IRAs on December 31, 2019 (required to be present on line 6 of Form 8606), it's likely that much more of the Roth conversion is taxable and a significant amount of her basis in nondeductible traditional IRA contributions remains to reduce the taxable amount of future traditional IRA distributions.
