Roth 401K's do have an RMD. In order to avoid it, it has to be converted to a Roth IRA. The para. below is from the IRS.gov site.

What types of retirement plans require minimum distributions?

The RMD rules apply to all employer sponsored retirement plans, including
profit-sharing plans, 401(k) plans, 403(b) plans, and 457(b) plans. The RMD rules also apply to traditional IRAs and IRA-based plans such as SEPs, SARSEPs, and SIMPLE IRAs.

The RMD rules also apply to Roth 401(k) accounts. However, the RMD rules do not apply to Roth IRAs while the owner is alive.