It's in the nightly builds, although when they announced it they (bizarrely) received a lot of hate for it, so I'm not sure they'll continue development.
Because It is better for reading on websites. Normally there is just a ton of space to the sides of the text, and it would make more sense to actually use it.
Why not an extra bar like all other browsers?
What... do you mean? They have the top bar like other browsers. A lot of other browsers have vertical tabs now too.
I would really like to get some shortcuts for some sites.
Add them then?
Also, I think tab groups are way more important.
I never said they aren't. Also, they do have container tabs, they just hide it in about:config.
Another security feature added is the blocking of downloading files from URLs that are on lists of potentially dangerous content.
Yeah, I'm not sure blocking HTTP downloads by default is a good idea, I mean many offices probably have some internal legacy HTTP only sites that nobody dares to touch, that are perfectly safe being HTTP (if you have hackers inside your network a simple intranet site spoofing is your least problem), and disabling this security option might have a lot of wider repercussions
Edge has started doing that too, whenever I download something from my Home Assistant instance while at home I have to rightclick and say that I really want to download it.
As long as such an option is available its not too bad.
It's not just about that, people will be disabling the feature that is potentially beneficial to their security, disabling http downloads from http sites is just an extension of blocking http downloads from https sites