Nah, very unlikely Bing triggered this. Submitted sitemaps in Bing Webmaster Tools don't talk to Google's index at all - different systems, different signals.
What you're seeing is classic timing noise. Google's SERP reshuffles happen constantly, and a 2-3 day lag after a sitemap submission is pure coincidence. Seen this a hundred times with affiliate sites - people chase ghosts instead of looking at the real data.
Start digging into the drop properly:
- Was it sitewide or just a handful of pages?
- Which queries tanked in impressions?
- Any coverage or indexing changes in GSC?
If it's page-specific, it's usually intent mismatch or competitors eating your lunch. If it's sitewide, you might've caught an algo update bouncing around.
The timing feels suspicious, I get it, but this is textbook correlation-not-causation bullshit. Focus on the diagnostics, not the mystery.