OK So I'll just upload it.
My afpub is consisted of imported PSD files. Expected behaviour is that Photo Persona's Rectangular Marquee Tool's selection shall be aligned to actual pixel. But if there is a page of different size existing, only in the first page (of different size) selection behaves normally. Currently my workaround is editing in Photo then switch back to Publisher.
In order to reproduce, open xen-comic-00 (6).psd in Affnity Publisher and right click on Page 1 -> Add Pages from file -> put xen-comice-00 (1) portada.psd before. Then switch to Photo Persona. You would notice that in Photo Persona selection works normally in Page 1 (xen-comice-00 (1) portada.psd), but in Page 2 (xen-comic-00(6).psd) selecting is messed up, whether pixel alignment is enabled or not.
Copyright notice: These files are created by Andrés Barra (https://derideal.com) and licensed under CC-BY-NC-SA.
xen-comic-00_(6).psd xen-comic-00_(1)_portada.psd