What is destabilisation?

Definitions from Merriam-Webster

destabilize

transitive verb

1: to make unstable

2: to cause (something, such as a government) to be incapable of functioning or surviving

decline

noun

1: the process of declining

a: a gradual physical or mental sinking and wasting away

b: a change to a lower state or level

2: the period during which something is deteriorating or approaching its end

3: a downward slope

phaseout

noun

: a gradual stopping (as in operations or production) : a closing down by phases