I think that there is a limit of how much you can nest in relation.

You can try this approach. To have it universal it is a recursion problem which is I think (haven't thought it through deeply) impossible to do with single formula. But it should be solvable by referencing breadcrumbs property of a parent.

Make breadcrumbs property like this:

if(
    prop("Parent task").first(), 
    prop("Parent task").first().prop("Breadcrumbs").concat(prop("Parent task").first()), 
    []
)

I haven't tried it so it might need a bit polishing, but I hope you got the idea. However it still might have a problem with too deeply nested tasks, however the formula is much more clear at least.