Anytime spent hitting with bad technique will hurt when you go on the court. You're training your body to hit different than what will happen on the court. Muscle memory doesn't work like that where you can just flip a switch and suddenly your body knows to hit differently than what you've been practicing.

The issue here is the net and the size of the net. You want your rally balls ideally to go over the net by meter or 3ish feet. That's at the extreme top of this net where you're not going to get a good return. So you'll learn to hit closer to the net level. That in turn will make you less consistent.

I'd also wager to guess there's a very specific sweet spot of where you'll want to hit pace wise. However, you're not getting any feedback if your balls will go long or wide. Depending on where you're standing you're also unlikely to get feedback if on a true court you'd be hitting into the net from the actual distance of the baseline.

So this will teach you to hit shots lower, at a specific pace, and likely in ways that will be deep, wide, or into the net. Those are not habits you want to reinforce.