I mean, this isn't really a surprise. On many social media platforms, you get instantly banned/shadowbanned if you post an external link, if you can publish that post in the first place at all. From the platform's perspective, there is almost no incentive to allow external links (spam, leakage etc). There is no law to mandate that third party links must be allowed.

I don't like this but also don't see how this can be different in the real world.