Note: Test on Boost and Clean
Login as any user.
Click on your user menu and click " Preferences "
On your Preferences page, go to " Editor preferences "
Select " TinyMCE HTML editor " as your Text editor. Save changes.
Edit your profile.
Check the text editor for your profile's " Description " field.
Click on the " Toolbar toggle " to expand the editor's toolbar.
Check the icons in the toolbar's buttons.
Confirm that all editor button icons look correctly sized.
E.g.
Note: Be sure to purge caches before testing.
The following four TinyMCE icons are being displayed too small, so they appear to be dots instead of occupying the whole buttons:
Toolbar toggle
Prevent automatic linking
Insert moodle media
Manage embedded files
I think this only affects Boost, they looked fine in Clean theme.