I changed my browser and I can't see the pieces on the board

@TodoCalza
Try disabling all of your add-ons. Maybe it's a privacy add-on that is restricting necessary resources? I am using mobile Firefox for iOS and Firefox Quantum for OS X with various add-ons. The mobile version is slightly buggy in dark mode (fonts are not visible on certain screens) but it still works well. Good luck!

@sfumatosauce I installed Firefox following the installation recommendations, Maybe I should modify something, also I will verify if any complement is the cause of the problem. Thank you!