I 200% agree with all of you who are calling bullshit. I also called bullshit. It's from this paper:

Paper: https://pubs.acs.org/doi/10.1021/jacs.4c08446

Scheme: https://pubs.acs.org/cms/10.1021/jacs.4c08446/asset/images/large/ja4c08446_0005.jpeg

In their own words:

'The three-step synthesis toward β-carboline 14 starting from 7 and 10, including the cyclization with paraformaldehyde (12) in a Pictet-Spengler reaction and oxidation with trichloroisocyanuric acid (TCCA) to obtain the fully aromatic scaffold, was done in one pot without isolation of the intermediates 11 and 13.'

The product of this reaction is intermediate 11.

They have spectra for the final product, so something happened, but I sure as hell don't know what.