they probably don't want to be accountable for serious damage claims. They do it for people's attention. To materially disrupt data center construction you need a lot more than a single action

You can get 10% hydrogen peroxide and 32% acetic acid over the counter, so that's probably what they used

Peroxide is a base too. Add it to an acid and you get water.

Sugar water sprayed on the forms and reinforcement before the concrete is poured would work better.

they got their headlines, so it works

With their track record, I suspect they achieved absolutely nothing of value.

Which is on brand for them.