According to court documents filed in a lawsuit against the company, Apple knew its iPhone 6 and iPhone 6 Plus models were more prone to bending than previous iPhones. Internal Apple documents referenced by the judge acting in the case reveal that Apple engineers were concerned about the issue ahead of its launch.
https://www.notebookcheck.net/Apple-knew-iPhone-6-6-Plus-could-bend-more-easily-ahead-of-launch.305810.0.html