Close to throwing in the towel - Sudden 90% drop in SEO traffic and impressions!

My site last week saw a sudden drop in my SERP results. It was a big site few years ago and I lost all ranking slowly over the course of a year, but put it down to never updating content. Started to see lots of recovery over the last 2 months. But no lost all recovery last week instantly.   \- No warning on search console, \- nothing de-indexed, \- ran through many tools, no issues found, \- Lighthouse is giving me 90-100 on every page for SEO, best practices, accessibility \- 80 + on performance on all tested pages \- link building limit to about 15 PR links a month \- cant see any news about algorithm updates or search volatility \- im having new  content added daily, and updating old content daily to. \- I have a lot of pages 800 or so, could this be an issue?   If google wants to destroy your traffic/ business, they really should tell you why!   Suggestions anyone?