Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
This is quite unexpected, does your search analytics data appear under Rank Math > Search console?
Please check your GSC stats and analyze your traffic. Notice when you installed Rank Math and when the decline started. If it was almost instant, then you must have No Indexed some posts accidentally.
There have also been a lot of Google updates in the last couple of months so this might just be a co-incidence. There is nothing in the SEO plugin that would make your website decline in rankings or get lesser traffic.
Looking forward to helping you. Thank you.
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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.