Some of the language flag SVGs have displaying issues in IE11.
The problem appears for example with the French language flag (/typo3/sysext/core/Resources/Public/Icons/Flags/SVG/FR.svg). This happens because of a missing "viewBox" attribute on the "svg" element inside the svg file.
Working flags like the one for German (/typo3/sysext/core/Resources/Public/Icons/Flags/SVG/DE.svg) have this attribute and have no displaying issues.
Some of the language flag SVGs have displaying issues in IE11.
The problem appears for example with the French language flag (/typo3/sysext/core/Resources/Public/Icons/Flags/SVG/FR.svg). This happens because of a missing "viewBox" attribute on the "svg" element inside the svg file. Working flags like the one for German (/typo3/sysext/core/Resources/Public/Icons/Flags/SVG/DE.svg) have this attribute and have no displaying issues.
Stackoverflow answer regarding this issue: http://stackoverflow.com/a/27971837/2987242
The Flags without the "viewBox" attribute also have a different (rectangular) layout in Chrome (see screenshot)
Solution: Add a "viewBox" attribute on every SVG missing the attribute.
See also https://forge.typo3.org/issues/79595