I love the folder feature to aggregate my tabs.
Unfortunately, within a folder, opening a new tab with the shortcut doesn’t add it in the folder 
I have to drag it back into the folder it should belong and that bother me
I would love to set by default that the new tab opens in the folder I am browsing, or next to the tab I am. CMD+T with not worrying to have to reorganizing it afterwards.
What do you mean by «folder» ? Bookmark folder or tabs group ?
Yes, the tabs group.