This is a common sentiment echoed regarding many different topics across the human experience, so I want to, for the sake of discussion, try and articulate exactly what are the two sides of this scale that might be worth debating. David Putnam defined "intra-" and "intercohort" like this in
Bowling Alone.
> Because generational change will be an important theme in our story, we should pause briefly here to consider how social change and generational change are interrelated. As a matter of simple accounting, any social change—from the rise of rap music to the decline of newspapers—is always produced by some combination of two very different processes. The first is for many individuals to change their tastes and habits in a single direction simultaneously. This sort of social change can occur quickly and be reversed just as quickly. If large numbers of Americans, young and old, fall in love with sport utility vehicles, as they did in the 1990s, the automotive marketplace can be quickly transformed, and it can be transformed in a different direction just as quickly. Sociologists sometimes call this type of change “intracohort,” because the change is detectable within each age cohort.
> The second sort of social change is slower, more subtle, and harder to reverse. If different generations have different tastes or habits, the social physiology of birth and death will eventually transform society, even if no individual ever changes. Much of the change in sexual mores over the last several decades has been of this sort. Relatively few adults changed their views about morality, and most of those who did actually became more conservative. In the aggregate, however, American attitudes toward premarital sex, for example, have been radically liberalized over the last several decades, because a generation with stricter beliefs was gradually replaced by a later generation with more relaxed norms. Sociologists call this type of change “intercohort,” because the change is detectable only across different age groups. Precisely because the rhythm of generational change is slower paced, it is more nearly inexorable.
I almost want to say that you're arguing internet disappointment (perhaps "perceived enshittification") is a predictable, generational intracohort phenomenon that applies to _all_ familiar aspects of one's life and not, conversely, an intercohort phenomenon through which generational attitudes remain constant, and the world changes around us.
On second thought, I don't think this is the right dichotomy to codify the common sentiment you've expressed. If somebody more learned happens by, please assist.
Edit: I think the term I am looking for is "Age-period-cohort analysis (APC analysis)," which I know nothing about.