I think "anticompetitive" is not the right word to use, unless you've got a lot more to back that up. The facts point more toward the TSMC+Apple dominance being a situation that is somewhere along the lines of "market failure" or "natural monopoly": chip and fab R&D costs have grown so large that only a handful of entities can even theoretically compete at the leading edge, because the total global market for semiconductors is finite. You don't need to postulate anticompetitive behavior to explain the shrinking oligopoly, because the fundamental dynamics of the semiconductor market already predict that trend.
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I think "anticompetitive" is not the right word to use, unless you've got a lot more to back that up. The facts point more toward the TSMC+Apple dominance being a situation that is somewhere along the lines of "market failure" or "natural monopoly": chip and fab R&D costs have grown so large that only a handful of entities can even theoretically compete at the leading edge, because the total global market for semiconductors is finite. You don't need to postulate anticompetitive behavior to explain the shrinking oligopoly, because the fundamental dynamics of the semiconductor market already predict that trend.