way too low.
Your CTR seems way too low,
Your CTR seems way too low, I would say this doesn't look legit and if you didn't buy those impressions then maybe someone tried to ban your AdSense account(It could happen too, it makes you look like you buy those impressions)... Other thing could be someone just didn't spell correctly a website and accidentally entered yours in his blog... Maybe YouTube channel... I would believe this was legit if it had 6 000 clicks, but 0.4% is way too low to be true.