The case of Champlain Towers, Miami FL

https://abcnews.go.com/US/surfside-condo-collapse/story?id=80068218 

Back in 2018, structural engineers conducted an inspection of the building and reported that "...among other things, concrete structural damage to concrete structural slabs on the pool deck due to failed waterproofing". Estimated repairs would cost more than $9m, but those repairs were never completed.

The building suddenly collapsed on June 24th 2021 in the middle of the night whilst residents were sleeping. 98 people died. The case is still under investigation but Wikipedia has a summary of the key points.