I think we have started to identify a fallacy used by libs that goes along these lines:

Proposition X has moderate evidence that it is true. However, libs believe that X needs to meet certain standards in order to for them to be 100% certain that it is true. Because, we don't have proof that X is 100% true, there is "no evidence" or "scant evidence" for X.

Examples:

Trump, without evidence, asserts that migrant caravans are approaching the southern border.

The Food and Drug Administration on Sunday issued an emergency use authorization for hydroxychloroquine and chloroquine, decades-old malaria drugs championed by President Donald Trump for coronavirus treatment despite scant evidence.

Philosophy pedes help me here. I believe this is an informal fallacy?

Edit: "Argumentum ad libtardum" is Latin for "argument from liberalism"