The planets around LHS 1903, a cool faint red dwarf star, begin as expected with a rocky planet orbiting close by and then two gas worlds. ESA’s CHaracterising ExOPlanet Satellite (CHEOPS) then reveals a surprising fourth planet at the system’s outer edge which is rocky, rather than gaseous.

It sound like Pluto.

I think they’re missing something fundamental:

the outer rocky-planet could well have formed closer, but been lobbed out, by gravitational-interaction.

There’s NO reason to believe that every body in a current solar-relative-position “always” was there.

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