Edit gif

[Luciole]

Thanks for your anwsers, all three !

Sorry, indeed, there is a lack of information ! I have an example with that gif : https://zupimages.net/up/22/17/bvcf.gif
Okey, there is just a few layers (33) but it's still a good example.
I want to erase some sparkles, not the totality, just a little at the bottom.

I tried a layer mask on the first layer then, I tried a layer group to apply the same effect on the rest of the layers (32). Also, I tried to erase stupidly, with the eraser, without a layer mask. But it doesn't work. I think the transparency doesn't work on the gif, is it true ?

Here is a screenshot :

https://www.zupimages.net/up/22/17/0cuc.png

I erased without a layer mask, and I wanted to use layer group to apply the same effect.

On that screenshot, I forgot to do that : Filters -> Animation -> Unoptimise
Maybe it's the reason, I don't know.

Thanks for your help !