Its back on Google Play now. From Organic Maps update on Mastodon:

> Good news! Organic Maps appeared again in the Google Play store last night without any notifications or explanations. We are grateful for your feedback and support!

> Stay tuned for the upcoming update, which is already available for iOS.

> Let's make the best maps for everyone together

> https://play.google.com/store/apps/details?id=app.organicmap...

Link to the above quoted post from Organic Maps: https://fosstodon.org/@organicmaps/112982935184446753

Discussion on HN yesterday: https://news.ycombinator.com/item?id=41272925