Http parameter pollution

noob here,

Ive been reading through lots and lots of public disclosures as part of my learning and one I’ve come across is parameter pollution, I’m looking at 2 reports in particular here and cant for the life of me understand what the particular vulnerability is

hackerone doesnt seem to have a forum so i cant ask there

I’ve read the OTG-INPVAL-004 from OWASP and just cant conclude why these reports are valid?

can any clarify this please?

They considered a vulnerability because the attacker can tamper with the url and then send this new url to a victim. After this, if the victim tries to share it via facebook, it will end up linking the website of the attacker instead of the original website.

Thank you kindly Herrera