Something that is not explained adequately or at all by physicists is that there is absolutely no requirement that the so-called laws of the universe be unifiable. The idea of a “Grand Unified Theory” is extant because it’s beautiful (they think), not because such a thing is the only possible configuration.

It’s also possible that gravity and quantum mechanics (and other aspects of the universe) are incommensurate and can never be unified. There is no scientific problem with this if that’s the way the universe turns out to be.