This is interesting. ECB has always been cautious about Bitcoin and has expressed concerns about its potential impact on financial stability in the economy. It even considered BTC as a highly speculative asset and called for a global regulation. Not sure if being threatened is the right right to describe ECB but bitcoin's something that they wouldn't allow to expand its role in the economy without getting regulated.
It's edited as per my understanding just to troll thr banking system and make people aware that Bitcoin is much useful then banks.The banking system has been trying to make you fool and some btc enthusiastic might have highlighted this image on twitter to promote a conversation about it and there must be mentioned about it somewhere because banks would not promote btc at this level on their own building.
I think that flashing Bitcoin logo on ECB building is used by supporters as a form of publicity or protest. It is a way to raise awareness about the potential of cryptocurrencies that most people don't know yet. Those who have faith in bitcoin believe that it represent a decentralized alternative to traditional currencies that we have that are controlled by the government. The way I see it, edited or not, that logo on the building is a form of expression and a way to draw attention to an alternative financial system.