I never cared about vertical tabs, but I know that this is something that many people have wanted for a very long time. How long has this been actively in the w

I never cared about vertical tabs, but I know that this is something that many people have wanted for a very long time. How long has this been actively in the works? Is it just a coincidence that this finally got done only after all the negative press Firefox got following their pivot to becoming an AdTech company which generates revenue through the constant surveillance of its users?