Ah yes, "boiling the frog". It's a colloquial metaphor in English (possibly other languages?).

The idea is that if you throw a frog in boiling water it will attempt to jump out immediately, but if you set one in water at room temperature and slowly bring it to a boil it won't notice what is happening and allow itself to be slowly boiled to death.

A real world example of the metaphor would come from large corporate "engineering process" steps for workflows. Things usually start out simple, with there only being say, 10 unique steps in a process. Then new steps keep getting added in each year as "problems" or "gaps" in the current process are identified. After a decade or so the 10 steps in now 100 steps, and the veteran project managers at the company are baffled as to why what used to take 4 days now takes 4 weeks. Like the frog, they didn't notice the slow gradual change, but as human beings, they notice the big change when they compare now to a decade ago.