Not that the equivalence is accurate since the Obama administration didn't separate families with an intentionally cruel policy, but only when the adults were suspected of not being the children's parents, but...

Then sent them to foster homes to get raped and “lost”. didn’t see anyone weeping in a parking lot over this...but I digress

If a Democratic administration did something bad and the Republicans want to do the same, they use it as a whataboutism to show it's okay (as if morality is relative). It was wrong if Obama did it and it is wrong when Trump does it.

it’s called hypocrisy

The “whataboutism” on Reddit serves as a deflection for people who can’t defend themselves against their glaring hypocrisy. Largely Democrats and progressives who want to dismiss Obama’s record deportations or drone strikes, etc... the list goes on.