This is why the divine hiddenness problem is so underrated, and why it's not just a facet of the problem of evil, but also a distinct argument with independent force. Any general explanation of divine hiddenness necessarily reduces the force of every theistic argument (except maybe for ones made on purely a priori grounds, but those are all pretty terrible anyway), since they make the phenomena appealed to by theistic arguments unexpected on theism - we should expect God to instead hide those phenomena just like he does with all the other evidence for his existence. The theist is free to claim that these phenomena still provide some evidence for theism, since even if divine hiddenness renders them less expected, they would be less likely still on atheism, but an honest theist has to admit that divine hiddenness reduces their force. The only way around this would be if theists had an explanation for divine hiddenness that wasn't fully general - i.e., not just a claim about how much total evidence God would allow, but an explanation that only implies that certain kinds of evidence would be lacking. Such an explanation would have to predict that the specific phenomena that theists point to as arguments for God (in this case, a small collection of Catholic miracles) would still be allowed, while all the other potential ways God could reveal himself would be disallowed.

I also think theists who use, "God doesn't want the evidence for his existence to be too strong," as an explanation for the lack of evidence, and especially as a patch for holes in their own arguments (like the imperfect preservation of the Lanciano relic) don't realize how incredibly silly this looks from the outside. I see no difference between this explanation and a conspiracy theorist dismissing any counterevidence as just part of the conspiracy, or a creationist dismissing evidence for evolution as actually being planted by Satan (indeed, this example is isomorphic to the dismissal of non-Catholic miracles by claiming they were performed by demons). If you add to your hypothesis an auxiliary claim that allows you to dismiss any counterevidence or any weaknesses in the evidence as actually being expected, then your hypothesis immediately loses all predictive power, and therefore all evidence in its favor (it's a simple theorem of probability theory that if no observation would be evidence against your hypothesis, no observation can be evidence for it either).