I use and enjoy it too, but sadly it is not FOSS.

That’s a separate OS setting. Signal itself has its own setting for which content is actually sent in the notification.

Users who aren’t verified as adults will not be able to access age-restricted servers and channels, won’t be able to speak in Discord’s livestream-like “stage” channels, and will see content filters for any content Discord detects as graphic or sensitive. They will also get warning prompts for friend requests from potentially unfamiliar users, and DMs from unfamiliar users will be automatically filtered into a separate inbox.

That shouldn’t be too restricting for people using discord to chat with their friends though.

This toot is a response to a very similar question from someone else.

Also keep in mind, LTS versions always offer 5 years of support, so the current PopOS 22.04 LTS will receive support until April 2027, and the new PopOS 24.04 LTS will receive updates until April 2029.

PopOS isn’t going anywhere?

They’ve been working on their own Desktop Environment (COSMIC) for quite a while, an alpha and a beta already exists and the release is planned for December 11th (source).