Hello,
Thank you for contacting the support and sorry for any inconvenience that might have been caused due to that.
Rank Math doesn’t change the HTML of your page; It’s might be theme behavior; please kindly get in touch with your theme developer and ask them to provide the appropriate solution. Or, if you are using the elementor to build the podcast block, Kindly change the settings inside the block to <h3>.
If the issue persists, We might need to take a closer look at the settings. Please edit the first post on this ticket and include your WordPress & FTP logins in the designated Sensitive Data section.
Please do take a complete backup of your website before sharing the information with us.

It is completely secure and only our support staff has access to that section. If you want, you can use the below plugin to generate a temporary login URL to your website and share that with us instead:
https://wordpress.org/plugins/temporary-login-without-password/
You can use the above plugin in conjunction with the WP Security Audit Log to monitor what changes our staff might make on your website (if any):
https://wordpress.org/plugins/wp-security-audit-log/
We really look forward to helping you.
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.