The Germans used a flak gun against tanks. It performed well.
The 88 was probably the best multipurpose land gun in World War 2. The US Naval 5 inch gun was the other top ranked dual purpose weapon. I don’t think these 100mm AAA guns are in the same league. It was a standard caliber for Russian anti-tank guns for years. It was also the standard gun on T-55 tanks. Wikipedia does claim that the KS-19 has good capabilities against ground targets.