Currently, pinned tabs can be closed with Ctrl+W / Cmd+W, and we've clarified this is the intended behavior.
A Chrome user recently suggested that we could have a "Hold X to close", similar to the Chrome/Chromium default behavior for Ctrl+Q/Cmd+Q for quit. It would look something like this:

Pin TabPinned tab closes 鈽癸笍
User should have to hold shortcut to close
100%
Brave | 0.68.56 Chromium: 75.0.3770.90聽(Official Build)聽nightly(64-bit)
-- | --
Revision | a6dcaf7e3ec6f70a194cc25e8149475c6590e025-refs/branch-heads/3770@{#1003}
OS | Mac OS X
https://github.com/brave/brave-browser/issues/4988#issue-458162978
Approach to solve inadvertently closing pinned tabs via ignoring CMD + W pref, might be a good way to go to instead of a warning.
cc: @rossmoody
+1 from me - a great idea that would be very helpful!
+1. It gets little annoying when a pinned tab gets closed accidentally. Would be a very helpful UX improvement.
+1 from me yes please
+1
Much prefer the preference option. Often pinned tabs are closed when you spam/hold Cmd+W so having a message would probably be ineffective. What exactly is the point of pinning of they are so easy to close?
Someone suggested restoring the tab, but if you're like me and have a mix open on SoundCloud or whatever, it doesn't restore the playback.
Most helpful comment
https://github.com/brave/brave-browser/issues/4988#issue-458162978
Approach to solve inadvertently closing pinned tabs via ignoring CMD + W pref, might be a good way to go to instead of a warning.