I shall be the turbo-autist then:

Strictly speaking, there IS two concurrent seasons of the show, one mainline, and one comedy one Youjo Shenki, which covers the more comedic and slice of life elements from the LNs. They're micro-episodes, and more or less follow the same timeline as the main series, what is being done in off-hours, things being done by side characters, etc.

Silly little asides, like addressing why no one in the squad tries hitting on Serebrinakov, what foods people like, outside perspectives on the Devil of the Rhine, etc.

So saying it has two seasons and a movie, isn't technically incorrect.