The flag

Somebody also pointed out that the admin in question has a black-and-red horizontal flag in his profile, calling it a "Nazi-adjacent flag" that justifies blocking the instance. This flag has been a symbol of Ukrainian resistance for centuries, as seen on Repin's painting about Cossacks. Its red color indeed symbolizes blood (of workers and peasants against empires), similarly to how on socialist flags red stands for martyred workers. And its black stands for the ground from which we grow, which the empire tries to steal but which we defend... It's like the polar opposite of the irredentist, chauvinist usage of these colors elsewhere.

This flag was in particular used by Ukrainian insurgents against Nazism and Bolshevism between WW1 and WW2, and later. As you know, anti-imperialists of Ukraine (UPA, red-black flags) were enemies with anti-imperialists of Poland (AK, white-red flags), because despite they both fought against same empires, it was a very dirty multi-national war. Polish irredentist and Ukrainian "integral nationalist" sentiments were fueled against each other to ensure war crimes happen and we exhaust each other and both lose. Both the Poles and the Ukrainians recognized this, but not until late 1940s, and lots of lives were lost in this mess on each side. The red and black flag remains in use, standing for the remembrance of the earlier battles against empires, and the hope for success of the current one. It is not chauvinist pride, despite anyone's attempts to portray it as so.