The sidebar in Opera GX opens over top of the left side of the open webpage instead of the sidebar taking up its own section of the browser window separate to the webpage. This makes vertical tab extensions unusable.
In normal opera the "sidebar extensions in browser sidebar" flag can be disabled to fix this, but Opera GX does not seem to have this setting available.
gif showing the problem: https://i.imgur.com/DPQXvv9.gifv
I can't possibly use a browser without vertical tabs anymore so this behaviour ruins GX.