https://www.fidelity.com/learning-center/personal-finance/secure-act-2
"529 Plans. After 15 years, 529 plan assets can be rolled over to a Roth IRA for the beneficiary, subject to annual Roth contribution limits and an aggregate lifetime limit of $35,000. Rollovers cannot exceed the aggregate before the 5-year period ending on the date of the distribution. The rollover is treated as a contribution towards the annual Roth IRA contribution limit."