For a normal Windows shortcut, the thing to inspect is:
Right-click the Brave icon/shortcut.
If it’s the taskbar icon, right-click it once, then in the little Jump List that appears, right-click the “Brave” entry again.
Choose Properties.
Look at the Shortcut tab, particularly:
Target
Start in
possibly Arguments if present.
For a normal Brave installation, the Target should point to brave.exe (with appropriate installation path), and you would be looking for something suspicious appended after the executable - example using a Facebook URL:
The executable path is enclosed in one pair of double-quotes, and the URL is a separate argument enclosed in another pair of double-quotes.
IF no luck so far, then …
Creating a new, user profile provides a clean slate, allowing you to compare performance without interference from your primary user profile’s configuration.
Brave Browser (Menu --> More tools --> Add profile). When creating:
Make no appearance adjustments other than to set user profile color at brave://settings/manageProfile.
Do not import anything.
Do not add any extensions.
Do not make any adjustments to content filtering at brave://settings/shields/filters.
Do not allow/enable any Brave Browser “bells and whistles” such as Brave News, Brave Rewards, Brave Sync, Brave Talk, etc.
After you create that new user profile, Exit / Quit everything and Restart the computer … and then start up Brave Browser and choose the new user profile for testing your issue.
If your issue seems to be resolved, then you may have at least one extension that is the cause.