Site dropped from Google index

Good afternoon, someone in the group knows how to solve a de-indexing issue, something is happening to me with my site., I have always come out in the first places in google for more than 20 years and a few months ago the index simply disappeared from the search and now only the positioned external pages appear. do you have any idea how to fix it?

your comments would be very helpful for me

Have you made any particular changes to your website recently? No matter how minor it was, tell us about it.

What does Google Search Console tell you?

Is your site connected to Google Analytics and Google Search Console? That would be the first step in figuring out where this issue is.

De-indexing in SERPs could be the result of anything from technological SEO issues on your site, duplicate on page content, or simply having more competition for the keyword.