Flag ban regardless
The background of the ‘flag ban’ is that countries must maintain control over their flags, and the public must not be misled about the origin of the products.
Even if you make the flag small, registration still is prohibited. Below are two rejected trademarks.
EU external flag
Although it is the European trademark register, flags from outside the EU are also taboo, such as this trademark with the Canadian ‘maple leaf’.
And if the image no longer even resembles a flag, the colour combination can still be seen as a ‘flag problem’. This Italian trademark was also refused.