It is impermissible to roll funds from one employer's traditional 401(k) account to the designated Roth account in another employer's 401(k) plan. You'll need to contact to the plan that received the rollover and have them make the correction (treating the deposit into the designated Roth account as an excess contribution, making a gain/loss-adjusted distribution, and allowing a late rollover of the original distribution to the traditional account under IRS Notice 2020-46) unless the funds were originally properly deposited into the traditional account the receiving plan and subsequently moved to the designated Roth account in that plan by In-plan Roth Rollover.
