I contacted Fiverr support about a technical problem using the website with Firefox and I was told:
“Please note that Fiverr was developed to work optimally with Chrome and other browsers can cause issues from time to time.”
My suggestion is for Fiverr to design its website so that it will work properly when using Firefox.
Update: Please also provide support for Microsoft’s Internet Explorer browser. I have just found a bug using Fiverr when using Internet Explorer.