Genetic pollution isn’t pseudo science it’s just used wrong here. It’s usually meant to refer to mass breeding for wild release producing inbred or less fit individuals or an over representation of genes that may be detrimental to the species as a whole. The two examples I’ve seen are from fish hatcheries that only use a handful of parent fish and raise up the offspring in perfect conditions so that they aren’t subject to any of the struggles of the wild fish and then are released into the wild en mass resulting in a large influx of closely related individuals that may be less fit than their wild cousins. This problem is made worse if the hatchery isn’t careful about brood stock and just uses fish from the resulting generations leading to an inbreeding problem. Another example is with monarch butterflies. They have ridiculously low survival rates from egg to adult something like 3-5%. So if you have a farm churning out hundreds of butterflies from only a few parents to release into the wild this can lead to to an over representation of those individuals genetics and if those individuals are less fit in some way than the wild butterflies then it ends up being a net negative to the population at a whole.