Software quality has seriously declined across the board, from Spotify to Slack to core operating systems like Windows and macOS. I think a major factor is corporate culture, which largely ignores software quality. Another issue is that many engineers lack a solid understanding of CS fundamentals like performance, security, and reliability (perhaps this is why many are not able to solve basic algorithmic questions like linked lists or binary trees during interviews)..
I've seen code written by so-called "senior" engineers that should never have made it past review; had they simply paid attention in their CS 101 courses, it wouldn't exist.
On top of that, as long as poor software quality doesn’t hurt a company's bottom line, why would executives care if their app takes 20 seconds to load?
Consumers have become desensitized to bloat, and regulators remain asleep at the wheel..