Sabaton regularly gets accused of being right-wing because of things like putting out an album about Karl of Sweden, or singing the Swedish Anthem in concert, or writing a song that explains, with sympathy to the german people, why an evil, charismatic, and ultimately incompetent man was able to seize power.
I'll note one thing regarding the "Socialism" being real socialism. Especially as it's clear they're trying to stay neutral, and there are many who a decade ago praised hte "successful" socialism of Venuzuela who now insist it wasn't "real" socialism.
Yes, Hitler was an opportunist who would wear any clothing needed to prey on the sheep, but this was not the era where communist dictatorships tried to pretend to freedom and deomacracy by putting "democratic" in their names. Progressivism and fascism were on the rise. Taking on that label as a marketing strategy might be expected, vice avoiding some other label for the negative connotations, except...
I've noted before that not all government is socialism. It's about the focus. Leaving aside how the social policies were supposedly right wing (because Germans as the class instead of workers makes everything different to the left...), what difference does it make if the Nazi party allows a businessman to "own" an industrial plant or the Communist Party appoints a manager to make money and privileges out of his position of power? In either case the government tells the businessman not only whether they can stay in business, but what they cannot produce, and what they must produce. Getting a business permit wasn't merely a matter of registering for taxes and safety/health/etc., but literally a question of whether you'd be allowed to operate a business at all. If the Nazi party didn't think it needed pots and cooking implements for its soldiers, you would not be allowed to start a business making those supplies.
The government was the beginning and the end.