+1

(the) shifting sands (of something)
used to describe a situation that changes so often that it is difficult to understand or deal with "it"
https://www.oxfordlearnersdictionaries.com/definition/english/shift_1?q=shift 1
In the above explanation, is “it” necessary?

Comments  

No. Good catch.

When we construct the ‘so that’ clause, I think we need to use the object so as to make the meaning clear. It is not necessary in a ‘too … to’ construction.

Compare:
The situation changes so often that it is difficult to understand or deal with it. (the first it being a dummy subject)
The situation changes too often to be difficult to understand or deal with.