From an engineering perspective these sorts of acrylic tanks are a nightmare to ensure they are safe. The seams are impossible to inspect rigorously so the only real way of checking that they are safe is to load them with an excess pressure ( https://en.wikipedia.org/wiki/Hydrostatic_test ). This can't be done with a tank of this size so the engineers can only real fall back on giving the tank excessive safety margins. But those safety margins cost hundreds of thousands of dollars for a tank this big so maybe they were reduced.

All it takes is one incorrect application of a seam bond and a small crack will form. The crack may take decades to propagate with no way of detecting it. When the seam opens up a bit the crack will then propagate the entire length of the seam extremely rapidly and the whole tank will fail. Ideally failures would be slow and predictable but this is impossible with acrylic.

These sorts of failures have occurred before https://www.plasticstoday.com/materials/when-acrylic-aquariu... and will keep occurring as long as this type of construction is used.