This was not working for me on Windows 10 (21H1) with Sublime Text 4 build 4107. I added the commands directly to the
Default (Windows).sublime-mousemap, and also a
custom-named.sublime-mousemap file. Neither change had an immediate effect and restarting Sublime Text did nothing to enable the changes.
I was beginning to suspect this may be a newly baked-in feature of Windows 10 and looked into disabling scroll wheel zoom in Windows 10 itself.
Google led me to a solution in a locked Microsoft Community post in which the author mentions that this "feature" applies to pretty much every Windows application. I discovered that now even
Mouse Scroll Up/Down zoom functionality.
The solution makes use of AutoHotKey to disable the
Mouse Scroll Up/Down text zoom shortcut. The post linked above includes detailed setup instructions. In that post, the author's script will disable the mouse wheel text zoom shortcut throughout Windows.
I added a context-sensitive directive that will disable this behaviour only while the Sublime Text window is active.
#IfWinActive, ahk_exe sublime_text.exe
SendMode Input is recommended by the AutoHotKey developers and the line is included by default in a new script from a Windows explorer context menu.
As this post mentions Windows, and after 6 years is still the #1 result on Google for this issue, I'm posting here in hopes of helping other Windows 10 users.