Because you will not have a zero traditional IRA balance (in the rollover IRA) on December 31, 2022, any Roth conversion performed in 2022 will be largely taxable, with only a portion of your basis in nondeductible traditional IRA contributions being applied to the conversion. The rest of your basis will remain with your traditional IRAs to be applied proportionately to future traditional IRA distributions. Had the 401(k) not been rolled over to an IRA, allowing you to convert your entire traditional IRA balance and leave no funds in a traditional IRA on December 31, all of your basis would apply to the conversion.
To be able to apply all of your basis in nondeductible traditional IRA contributions you would have to roll of the pre-tax money that you have in traditional IRAs over to your present employer's 401(k). It's questionable whether that could be accomplished in the few days remaining in 2022, so you might want to wait until 2023 to do that and do your Roth conversion in 2023.
