I don’t know if this is posted in the correct section, please reply and tell me if it isn’t!
BEFORE RESPONDING SAYING NO, PLEASE KEEP READING.
I’ve went around the devforum looking up if you can reference Discord within your game. All I’ve seen is something along the lines of “It’s strictly against TOS to mention Discord within your game.” and I thought that was the end of it. But recently, I’ve played a couple popular games with the system saying something like,
[ System ]: Find any bugs or exploits, report it to our Discord server!
I read the entire thing, and I think you can, but it has to mention 13+. Don’t quote me on that, I’m not entirely sure though. I’ve seen other games like Ben’s Kingdom having a sign that says “Join our Discord server! Invite: [invite]”. So I think you can. Maybe review the terms of service. The only thing I can think of for no is “offsite links”, but that isn’t really a “link” since you can’t have links in a game that open up your browser and go to that page.
I’ve done some digging and found this page: PolicyService | Roblox Creator Documentation it says it can find the age group the player is in, but never tells us how.
I’ve also found this within the TOS
Directing Users Off-Platform
When using Roblox, you may not link to any external websites or services, except for : YouTube, Facebook, Discord, Twitter, and Twitch. Links to any of those approved sites must be wrapped in the applicable Policy API or listed in the Social Networks and Social Links settings of your profile or experience description page. Links that appear in locations where the API cannot be deployed - such as text chat - are prohibited. Any other links are prohibited, including:
Links that contain Roblox-inappropriate content
Partial links, filter-breaking, and permitted website links to non-permitted websites
Encouraging others to visit unpermitted external links
For their privacy and safety, we don’t permit users under 13 to share links
It doesn’t tell you the age group, just what links are viewable to the player; You have to use the service before displaying specific messages that relate to off-site applications.
local policyService = game:GetService("PolicyService")
local localPlayer = game:GetService("Players").LocalPlayer
local function canViewDiscordLinks(player: Player) : boolean
local success, output = pcall(function()
return policyService:GetPolicyInfoForPlayerAsync(player)
end)
if success then
if table.find(output.AllowedExternalLinkReferences, "Discord") then
return true -- player can view discord links
end
else
warn(output)
end
return false -- player cannot view discord links
end
print(canViewDiscordLinks(localPlayer))
QUESTS] Pet Simulator X! 
for example, there is a message that the system will say,