The nature of existence is that all phenomena are {impermanent}, {unsatisfactory}, and {not-self}.
See:
This is a core doctrine of Buddhism.
https://neuroticgradientdescent.blogspot.com/2020/01/mistranslating-buddha.html?m=1
“So when we engage with Anicca, we might think that in the long run of course things can’t stay stable. No, not in the long run! {Right now in your direct experience images of words and mental sensations of meaning are flickering by}. This is the Anicca to investigate!”
“When we engage with Dukkha, we might think that there’s a certain sense in which of course things aren’t satisfying. No, not in a certain sense! {Right now in your direct experience there are sensations related to aversive feeling tones that are being papered over}. This is the Dukkha to investigate!”
“When we engage with Anatta, we might think that of course our sense of what we control isn’t always aligned with what we can actually control. No, not better calibrated models! {Right now in your direct experience there is a sense of some sensations controlling other sensations}. This is the Anatta to investigate!”