This is definitely a problem. With multiple instances of the browser windows open. One in the background maximized and one in the foreground sized to access. I use a multi-monitor setup. and may also have a browser window open on the adjacent monitor.
When passing the mouse pointer over an area of the background window that is active, usually a JS list element, title bar, the full screen window in the background will grab focus and come to the foreground. This usually happens when the background window is on a website like Facebook or Twitter.
IMHO This is absolutely a problem of the background window having elements that are looking for a mouseover event while they should be anything but active in this way.
Here’s a link to the behavior. It is intermittent, I have been able to reproduce the symptom using this process. Open a window to an active page. YouTube Ebay Facebook Twitter. Add a tab. Move the tab out to a separate window and move the mouse back over the first window.
I am having this issue, too. Reports of this have been cropping up more and more lately. See my comment on this guthub report of the issue:
I am having this issue as well, and this report accurately describes my experience in reproducing it. There are many reports of this bug, most of which are from Brave’s Reddit forum. Support staff appears to be blatantly ignoring the reports. Sadly, Brave is such a good browser that I’ve suffered this bug for probably almost a year (this didn’t always occur), but it’s becoming so unbearable now that I am really considering switching exclusively to Firefox. This issue does NOT occur in Chrome which is also based on Chromium, so the issue is definitely with Brave itself.
Here’s a GIF showing the problem. Notice how the left window is initially on top. I then highlight the address bar and move the cursor offscreen to the window in the background. Without me clicking anything (ie, just hovering the mouse), it brings the other window to the foreground. However, even though the window on the left is visibly in the background, it is STILL the active window as illustrated by me typing into the address bar.