The keybinding editor should work for this. cmd+k cmd+s.

The issue is that the multiple keybinding have changed in a bulk. I will have to reassign all the bindings. Also need to understand why it's happened to prevent it from happening again. Eg Cmd+2 used to switch to the second tab, but now it splits the editor in two, which is driving me mad...

Someone might have published a keybindings.json restoring the old bindings. You are not the first one I hear is unhappy with the changes. As for why it happened, I think they changed their mind about what is good defaults, and took a decision. Disruptive, yes, but also sometimes necessary if you have vision for how the product should work.

I haven't find a way yet to toggle it back or to reassign to the behaviour. What's the way to go back to my previous version?

There are download links on their release notes: https://code.visualstudio.com/updates/

There seems to be an issue with the keyboard layout or smth similar. For instance lots of standard Cmd+keycombo bindings have changed to Ctrl+keybcombo. Or another way around too. I find it weird that VS code devs would have done this breaking change, perhaps I have inadvertently changed some layout in the VS Code settings.

Sounds a bit like VS Code somehow thinks it's being run on Linux or Windows...

I thought that too. But even on windows in a terminal I'd expect Ctrl-r to do the reverse look up, not to open some 'recent files' : )

It has always opened recent files for me. Unless the terminal is active.

Right, but when it's active it should not have changed