Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for any inconvenience this issue may have caused you.
You don’t need a separate Sitemap for a translated language. Polylang adds an hreflang tag to your posts, which helps Google determine that a piece of content is a translation of another post/page.
If the issue is happening to your main domain, could you also provide the URL for us to investigate further? You can include them in the designated Sensitive Data section:

It is completely secure, and only our support staff has access to that section.
I hope that helps. Thank you, and please don’t hesitate to contact us if you need further assistance.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.