- "I wonder if they could perform analysis over time and apply statistical models to subtract solar output from the data, knowing the orbital periods etc. But that’s just me being a layman here."

They do that in the paper. That's the "secondary eclipse", where the planet goes behind the star and they subtract the difference.

https://iopscience.iop.org/article/10.3847/2041-8213/acf7c4 [open access]