What to do with deprecation notices?

Can I totally ignore it then? I was worried that something would happen

There are these others that I have no idea what they are, I searched here on the forum but I couldn’t find a solution.

Sidekiq is consuming too much memory (using: 506.27M) for 'dex-forum.com', restarting

Detected rogue Sidekiq pid 3831279 mem 525602816, killing

Authentication failure! request_error: OAuth::Unauthorized, 403 Forbidden


Deprecation notice: Array types for custom fields are deprecated, use type :json instead (removal in Discourse 3.3.0)
At /var/www/discourse/lib/plugin/instance.rb:573:in block in register_topic_custom_field_type