AKA “Generic/Ambiguous deity fallacy”, is an instance of Motte-and-bailey fallacy and a special case of Straw-person fallacy. It consists on abusing the unfalsifiable existence of any unknown deity, to conclude that the existence of a specific god is “plausible”.
People committing this fallacy utterly ignore (either accidentally or intentionally) the fact that their gods are falsifiable, and most of them have been proven to not exist, so they resort to this technique to gaslight people into believing their claims aren’t ridiculous.
The ironic thing is that committing this fallacy is an act of heresy, so believers literally dump their personal gods in order to defend them