The ID claims around Irreducible Complexity propose a question.
If a complex of multiple proteins which accomplishes function X behaves
such that removal/deletion of any of the constituent proteins disable
that function, how could such a system have evolved by Darwinian evolution?

This is, and has always been, a strawman, for multiple reasons.

Only one of many such reason is addressed here.

Consider a "system" where a single protein can perform a function X'.
In this case, X' is in some way related to X but at some reduced effect.

Now let a helper protein arise that can bind to the first protein and
make it perform the function of focus a bit better. We still get the
function X' with out it, but with it we get X'' which is the new and improved function with a fresh mountain air scent. So it isn't even semi-IC, you
can remove a part and it still works.

But let this two protein system coevolve and it's not only possible, but likely that they will become codependent. The first protein will lose it's ability
to function without its 'helper' protein. It's likely it will lose the ability to
function independently because there are no negative consequences for
doing so. It and the helper protein are free to mutate to work better together even when the changes to the first protein reduce or eliminate its efficacy
to function independently.

This leads to a system that is a primitive for of IC. Remove either of the
two proteins and you lose function X'.

A quibbler can interrupt that Behe doesn't consider systems of only two proteins to be IC. Well that's a capricious definition on his part and you aren't thinking ahead.

Add a new helper protein to the two protein complex that performs function X'. It turbocharges to function X''. Repeat the above process where the
3 distinct proteins adapt to optimize their interactions with each other.
It is not only possible, but likely, that in optimizing how the 3 protein complex
interacts to perform X'', that the ability of just two of them to perform X'' or X'
or X is lost. It is likely to be lost because there are detrimental mutations, but what is detrimental is context dependent. What is detrimental to a standalone protein isn't necessarily detrimental to that protein when it is
in a protein complex.

As the instructions on the bottle say, wash, rinse, repeat.

We now have a 4 protein complex. First as 3 + helper but it then evolves to become a 4 protein IC complex where removal of any one of its 'parts'
will effectively eliminate function X'''.

If such a scenario plays out throughout an extended evolutionary timeline,
the cell's/organism's need for X(prime iteration) can change.

This could be made less abstract with a reference to a blood clotting-like function but I think that's overkill in this post.

And yes this is just an illustration of the Muller argument that Mark Isaak
has been explaining elsewhere.

The problem with Behe's argument is that he asks the question wrong. He
asks if you can take away one protein of a protein complex and keep the function. If not, he claims the system is IC and hard for evolution to produce. The claim has blinders on about how evolution works.

And asking "what changes can we make so that we can eliminate one
protein from the complex" is pandering to a dump concept. By the time
you're looking at it, there could be lots of adaptations to work well in a multiprotein complex. The outside of some proteins that used to be in
contact with water will have adapted to be in better contact with another protein. Many protein functions involve subtle conformational changes
that depend on the specifics. This will involve myriad interactions.

We can't model all that. Behe asserts some nonsense about how science is supposed to provide a detailed step by step explanation for how every
little change occurred along the way. That too is a strawman. Sure it
would be interesting, but it isn't necessary just to satisfy an assertion
about 'Intelligent Design' that is based on a failure to understand evolution.

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