If you don't file the 2020 form 8606, there will be no penalty.
In fact, as you have converted your IRA to Roth IRA and have made no more nondeductible IRA contributions since 2020, you have no use for the basis which wrongly remains on the last 8606.
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
