Does oat flour need to be kosher in general? Does Chabad eat Matzah made out of oats?
Oat flour is inherently kosher and requires no hechsher for year-round use (not for Pesach), if there are no added kosher sensitive ingredients.
Obviously, one must ensure the flour isn’t infested. If one is particular about chodosh, you would need to check the date code.
There are serious shaalos with oat matzoh since they are treated with heat in order to store them. There are available oat matzos that are not treated with heat. These should be used when necessary. Even so, wheat matzah is always preferred.