Hello @irina1975,
Thank you for contacting the support and sorry for any inconvenience that might have been caused due to that.
It seems to be working fine on our end:
https://i.rankmath.com/Nykm3D
Assuming you are using the latest version of all the plugins, themes, and WordPress (please update if not yet), it would seem like a conflict with one of the plugins or the theme you are using.
To determine that, please follow this troubleshooting guide:
https://rankmath.com/kb/check-plugin-conflicts/
Only the site admin would know and your users won’t be affected by this troubleshooting.
Looking forward to helping you.