Currently the only way to switch profile picture back to avatar is through website.

in-game workaround would be to take a new Gallery picture, apply, delete the picture from gallery, then wait for cache to catch up.

(idk if this fits better in Feature Requests or Bug Report)

On the old UI, you could set a profile picture override, but also clear it out. On the new UI, once you set a custom profile picture, you can never go back to just showing your currently worn avatar.

Currently a third party API tool or the website must be used to clear it and then you still require a relog to see it yourself.

[DeepL]

In the gallery tab, I can set any photo I want as my profile photo, but I cannot deactivate it.

I need a button to deactivate the profile picture.

[原文]

ギャラリータブにおいて、私は好きな写真をプロフィール写真に設定できますが、解除できません。

プロフィール写真を解除するボタンが必要です。