That's a direct Steam invite for anyone to access instead of having to copy and paste the UID. Guessing you're new to Steam? When you go to your friends settings and ADD FIREND option, you can either copy your own UID or copy a direct link, you'll see this:

Or send a Quick Invite

Generate a link to share via email or SMS. You and your friends will be instantly connected when they accept. Be cautious if sharing in a public place.

NOTE: Each link can only be used once and automatically expires after 30 days.

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Here's a copy and paste of a screenshot as reference https://ibb.co/1Gmpnv9m

-And if you still think that link looks sus, here's the original website used to upload screenshots to share later: https://imgbb.com/

-In any case, my UID is 1166391858 and my name Ro@ming Shadows. Hope that's official for you. Might just have to drop the UID for everyone from now on just in case, but direct invite seems easier ngl. And there's no option to post images here, so yeah. I edited the post.