You need to repair the PCB trace that blew out, which would be an argument to just replace the board all together. If I am incorrect however, that could be some sort of ferrous dust from a motor or shaft within the machine that is attracted to the electro

Why you took the washing machine apart? Is it because there is something wrong with its working?

It looks like a total blowout. That is, an over-current or over-voltage failure on both the components and the traces on the underside of the board.

Does the washing machine still work? I think this is rubber grit from the main belt operating the drum.

Thanks for your intelligence. Pretty interesting and useful.