I don't quite understand why these two hydrogens are the most acidic. From a hybridization perspective, these are connected to a $\mathrm{sp^3}$ carbon (I thought the more s character, the more acidic). So why is it not any of the other hydrogens (connected to $\mathrm{sp^2}$ carbon)?

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    $\begingroup$ Consider the structure of phenol, how stable is the phenoxide ion? $\endgroup$ – Waylander Oct 4 at 7:27

The two hydrogen atoms are acidic, but things change after one of them is lost. But I think that the question was aimed at the acidity of either of the hydrogen atoms and they are equivalent, so let's see why:

As you can see in the given figure that after abstraction of $\ce{H+}$ the conjugate base can resonate to attain aromaticity. It is this stability that makes the hydrogen atom acidic. Now to remove the second $\ce{H+}$ the story changes, but I would be leaving out that discussion as it has not been asked in the question.

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  • $\begingroup$ If the answer smoothens your path of learning chemistry, do take a moment off to accept it. $\endgroup$ – Tesla's Coil Oct 4 at 14:11

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