If this building was literally sinking since the early 90s it took this long for it to collapse that makes no sense. Our house foundation also sinks from time to time, been like that since day 1, its the soil..tried putting beams, etc doesnt seem to ever do the trick so every few years or so we start to see cracks here and there on the walls and at night and when it rains its harder to open for instance the bathroom door, but the house wont collapse..
However, it will almost certainly be found to be a contributing factor. To what degree, remains to be seen.
It's going to be a combination of factors including engineering/construction/maintenance as well as the ground it was built on.
On Guam it is called “Earthquake Settling” it makes the drains clog because after several years they don’t have enough slope. We had to have the main sewer line re-plumbed when we lived there.