Is investing in the "Golden Farm" website, which is dedicated to raising birds and selling their eggs, and which relies on inviting others and promises a fixed profit, permissible or impermissible (halal or haram)?

It is not permissible to invest in this website for two reasons:

Firstly, usury (riba). The participant pays money to obtain additional money without any real investment. Rather, it is merely a game of buying birds that produce eggs that are sold virtually. This is forbidden usury, whether the profit is known or unknown, and it does not conform to the conditions of permissible investment.

Secondly, gambling and Maysir (games of chance). This occurs through earning profits via referrals and inviting others, which falls under prohibited multi-level marketing if it requires paying money.

Therefore, one must repent to Allah and stop dealing with this website and inviting people to it, and advise those who have been invited to leave it.