What does this even mean? do you think that welfare is fascist?

The meme is about how socialdemocrats entire ideology is built upon “reforming” capitalism by implementing a welfare state to more evenly spread the profits of the super exploitation of the periphery. When those profits dry up so too does the welfare state which inevitably pushes them right or left to deal with the heightened contradictions. The meme is pointing out the unfortunate pattern of it almost always ending in a rightward shift (due to many factors). (It is also possibly a reference to the SPD and how them unleashing the freikorps on the KPD directly helped bring Hitler to power)

Thank you for breaking this down. Would it be fair to say that social democracy on a national scale can still be imperialist but social democracy on a global scale would actually be a good thing?

No. Social democracy needs superprofits from the periphery to fund the core. Capitalism requires exploitation to function. If every nation is the core, who gets exploited? The surplus value does not exist. When accumulation slows, the bourgeoisie abandons reform. They choose fascism to protect property. The SPD proved this when they sided with reactionaries against workers. Reformism tries to manage a system built on violence. It cannot work globally because the economic base forbids it. The only path is revolution. Seize the means of production. End the imperialist chain.