A pardon in law is a government decision that forgives a person for a crime, relieving them of some or all legal consequences of their conviction. It is often granted by a head of state, such as a president or governor, and does not erase the fact of the conviction but can help restore the individual's rights.
Legal immunity, or immunity from prosecution, is a legal status wherein an individual or entity cannot be held liable for a violation of the law, in order to facilitate societal aims that outweigh the value of imposing liability in such cases.
I still cannot understand the idea of Biden granting individuals who are not under investigation for anything, are not charged with anything, and have never been convicted of anything a 'pardon'. A pardon for what?
They are conflating a pardon with legal immunity. These are two different and separate concepts. The President can grant a pardon. But the President does not have the authority to grant immunity. This is not within his authority.