After further investigation, with the previous versions of powerbi.js (2.7.4) I would set a default filter like this:
Now, this command is wiping the default filters of the report as you can see in the example above. After making some tests I could verify that if I set the filter with "null" as string the filters are not affected.
So my question is: should I use the newer version visual.setFilters("[]") or visual.setFilters("null") or is this a temporary bug?
I have clients complaining about this already!