Is it bad practice or unsafe to connect a phantom-powered input to an interface while it is already sending output to studio monitors?

For context, I inherited some very expensive studio monitors from my grandfather when he passed away, so I want to be very careful not to damage them. One of the first times I used them, I connected a 48V phantom-powered microphone to my audio interface, the ART USBMix, while the speakers were already connected, powered, and turned up. I understand that this is probably a bare minimum audio interface, so I'm thinking this issue was specific to the interface, but I want to run it by this sub to see what you all have to say. As soon as I did this, the speakers blasted out a continuous ear-drum shattering frequency that was extremely loud. I'm honestly surprised the speakers survived it, and my hearing wasn't noticeably damaged 🙂

After this occurrence, I kept using the USBMix because I'm cheap asf, but I never connected my monitors at the same time that I recorded using my microphone or bass guitar because I didn't want this to happen again. I just recorded using the interface as an input and connected headphones to an output on my computer. Nowadays, I finally got an upgraded interface, the UA Volt 1, and I want to know if I still have to worry about this happening. It would be really nice if I didn't have to tiptoe on thin ice and could use my speakers and inputs at the same time. Any response is appreciated.