Hi @vadim_ivanov!
In your last node it should be data not ={{ $('On form submission').item.binary.data }}
Also you can try using a merge node with combine by position, and there connect input 1 as the form submission, and input 2 the output of your processing node if it exists in the bigger flow,
Um also you can try using a set field node after your form submission with “Include Other Input Fields” option so that this will carry the binary file forward and would not stop it.