Dialogs attached to a particular window should be 'transient' to that window. https://www.tcl.tk/man/tcl8.6/TkCmd/wm.htm#M64
It is an oversight that the window search and replace windows are not.
Modal windows, including the current Find in Files might just as well be.
PR 13869 for #37177 (aimed at a different symption) makes search windows transient, fixing this issue also.
If Find in Files were not modal, then it need not be transient to a particular window, and minimizing could be sensible. But this is a separate issue.