Grey outline on gifs with white background

[happytofu4]

I have been using Gifski for a while and it used to convert my videos with white backgrounds to gifs just fine, but now it is adding a grey outline to my gif. Help would be very much appreciated, thank you :)

[sindresorhus]

In every case like this in the past, it turned out that it's was in the original video too. Make sure that's not the case.