Why apps disappear from Google Play
Policy removals, account terminations, unpublishing and abandonment: the usual reasons, and how the data hints at which one applies.
Policy removals
Google removes apps that break its policies: deceptive behaviour, malware, misleading ads, missing privacy disclosures. They often come in waves after a policy change, visible as spikes in the removal log.
Account terminations
When a developer account is terminated, all its apps vanish on the same day. In the archive this shows as many removals from one developer on one date.
Unpublished by the developer
Companies retire old products or merge them into a new app. These are usually old apps with a long update gap, and sometimes they come back.
Abandonment
Apps that do not keep up with Google's target API requirements lose visibility and, for new users, availability. Many small apps simply stop being maintained.
Reading the signals
Look at the last update date, the developer's other records and the day of removal. The store never publishes the reason, so treat any conclusion as an inference.