What I think was going on: Bing opened an A/B test to test a feature (which explains why the author couldn’t reproduce everywhere). The new feature related to how search terms were classified as “Bing features”. Maybe it was some kind of threshold. Because of that change, searches for “chrome” were tagged as “Bing features” and therefore the flow for promoting Bing was triggered.

Ultimately the goal of such an experiment is to increase the uptake of Edge but they overshot it this time.