After re-installation the plus icon in dosen't appear in my firefox tools bar. And also there is no explicit setting option to add the extension in firefox tools bar. Means if you didn't add the extension to the tools bar during installation you will never be able to add the extension to you firefox browser tools bar.

I don't know if this issue is happening with others too. But it has already happened with me.

Specifically, after using this extension to submit solution directly from my VSCode.

Very useful plugin