If Sidekiq consumes too much memory, it can cause Discourse to restart, which may interrupt scheduled email jobs. Discourse includes an automatic restart feature if Sidekiq’s memory usage exceeds a defined threshold.
To address this, check the UNICORN_SIDEKIQ_MAX_RSS setting in your app.yml file. If the value is too low, consider increasing it.
For further discussion on this issue, you can refer to this topic:
Sidekiq is consuming too much memory - restarting.