Memory problem with Rails Postgres app

Having a recurring problem with a new to Fly.io Rails/Postres app. Two notices since uploading a few days ago.

Out of memory: Killed process 521 (ruby) total-vm:252144kB, anon-rss:117604kB, file-rss:0kB, shmem-rss:0kB, UID:0 pgtables:504kB oom_score_adj:0 and

Out of memory: Killed process 521 (ruby) total-vm:252144kB, anon-rss:117352kB, file-rss:0kB, shmem-rss:0kB, UID:0 pgtables:512kB oom_score_adj:0

The app works when I use it, so something is happening while not in use. How should I go about tracking this down? Never knowingly had a problem on Heroku, but I did upgrade to ruby ‘3.1.2’ and gem ‘rails’, ‘~> 7.0’ during the move.

It a low to no use app, so not critical. The site shows up immediately, so I guess it’s automatically rebooted.