1) Hiring standards have drifted downwards over the past 15 years. Google used to be super-elite, compact, do-no-evil, massive-profit-per-employee. It's now a 140,000 person organization, and at that scale, standards just aren't high. You have a team of dozens of incompetent people doing what one person used to do.
2) With COVID19, ad revenues have crashed. It's not clear the impact on Google.
3) The smart, ethical folks on top (folks like Larry, Sergei, and Eric) are gone, and replaced with professional managers. They were smart to pick an internal CEO, but most of their executive team comes from places like Microsoft, Oracle, or Morgan. Having known a number of professional executives, the key skill is climbing executive ladders and moving into positions of power, not running successful companies.
4) Their products are increasingly starting to crash-and-burn, especially in B2B. Their culture relies on automated systems over people, and their automated systems have taken down tons of mission-critical businesses. Automated works well at 1000 people supporting 7 billion in B2C (small elite team model), and not so well for a massive, 100k person company.
5) I've switched mostly to non-Google products because they're better for what I need. AOL was massive too at one point. Losing the tech edge is not good. I still use gmail.
On the other hand, their revenues have continued to rise exponentially since they started. So perhaps they're doing fine?
In google’s case you can see this boredom on Android, on the number of products announced and casually killed (they might be excellent standalone products but can’t move the needle on earnings for the benefit of Wall Street so why bother?).
Contrast this to early Intel in the Grove era: they were on top of the world with the memory business so they pivoted to something else. Google has had the same two products for almost 20 years. The later Intel has been more like that.
Another contrast: they don’t know what to do about the advertising downturn, so are cutting back on hiring and such, while FB is trying to double down.