You can still take a screenshot from the right click context menu in Firefox.
Sigh! - Thereto it got migrated. Kind of find-the-cow/hide-and-seek jest in the Firefox-team ? - Anyway, MANY THANKS, SEBURO !!
It really doesn’t make sense to me to have functionality changed without making it clear. I thought the feature was removed as well. I searched to try resolve the issue and I found official looking information that has not been updated to reflect the change so it was unhelpful at best. This page is still up with outdated information that doesn’t help. https://screenshots.firefox.com/