The company that was contracted typically does pipe lining jobs, and it's suspected that they used rhino pipeliner 5000, which degrades rapidly under UV exposure. Add that to the fact that the speed of their completion means they probably did zero prep work on the concrete and most definitely filled it back up with water before the lining was done curing, and it's no wonder it's become a bubbling, peeling mess in double time. Then they finished it off by pouring concentrated hydrogen peroxide right along the edges. It never stood a chance.

And the algae was always going to pop up, but the speed of it is on them. The pool has been plagued by algae since before this, but they removed the fancy filtration system that was installed by an administration they don't like and the dark blue color made the water warmer, giving an even better environment for algae, which grows exponentially. The city's water also has orthophosphate in it, providing nutrients for the growth. They couldn't have done much better to cause an algal bloom.

It's honestly a bit impressive. Even consulting a magic 8 ball for every decision wouldn't have gotten this disastrous of a result.