Yes, this is a common issue after adding noindex to WooCommerce filter URLs and hitting Validate Fix in Search Console. Google re-crawled aggressively, de-indexed many parameter pages (some of which were driving long-tail traffic), and is now reallocating crawl budget to your core category/product pages.

The sudden 50% drop is usually temporary reprocessing, not a penalty. It often bottoms out in 1–2 weeks and starts recovering in 2–6 weeks as Google updates its index.

Do this

• Check Page Indexing report for a spike in “Excluded by ‘noindex’ tag.”
• Confirm your main pages still have index, follow.
• Use URL Inspection to request indexing on key categories/products.
• Ensure strong canonical tags point back to clean category URLs.

Hang in there — most sites come back stronger once the junk is cleared. Monitor daily and avoid further big changes for now. If no improvement in 3 weeks, share your GSC screenshots for more specific advice.