webp export, contain all frames even if choose one tag export

[FeelPr]

Hello
When I export an animation in .webp,
the export_file.webp contains ALL the frames of the file, even if I choose to export only a tag.
It doesn't do it with gif export for example, only in webp.

I've posted on the Aseprite Discord (Feel#3478) , and someone (sansgraceee#6838) managed to replicate it,
my msg : https://discord.com/channels/324979738533822464/348146938530496513/1050419017111834754
confirmation : https://discord.com/channels/324979738533822464/348146938530496513/1051498156841504808

Aseprite and System version

• Aseprite version: Aseprite v1.3-beta21
• System: Windows10 x64