Hello
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
In this case, please also make sure to whitelist the IP 193.138.6.5
and the user-agent RankMathAPI/2.0.0; https://rankmath.com
.
Here’s a URL you can follow to fix this issue: https://rankmath.com/kb/api-http-400-error/
Let us know how it goes.
Thank you.
I apologize, but the problem was not solved with all these solutions provided, although I spoke with the hosting assistance and they told me that there is no IP in the blacklist, and I added the IP address to the whitelist, and yet I still suffer from this problem
Hello,
Please head over to your WordPress Dashboard > Rank Math > Status & Tools > Database Tools > and click the Clear SEO Analysis
and Remove Transients
buttons to flush the SEO Analysis cache.

Once done, clear your website and any server-level caching on your site before doing the SEO analysis again.
If the issue still persists, then 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/
Looking forward to helping you.
Thank you.