In 2014, the artist, represented by the company Pest Control Services, applied for an EU trademark of the image 'Flower Thrower' to prevent the use of this piece by a greeting card company. In order to be able to demonstrate that the sign was actually being used as a trade mark, Banksy opened a brick and mortar store last year where his works could be purchased through a surrealistic process. The greeting card company was of the opinion that they were allowed to use the work because the maker wants to stay anonymous. Because of the anonymity, Banksy cannot enforce the copyright on the work. And now as it turns out, the Flower Thrower cannot be protected under trade mark law either. 
A panel of three judges of EUIPO considered the shop to be insufficient to circumvent the non-use of the sign:
“Only then, in October of 2019, he opened an online store (and had a physical shop but which was not opened to the public) but by his own words, reported in a number of different publications in the UK, he was not trying to carve out a portion of the commercial market by selling his goods, he was merely trying to fulfil the trade mark class categories to show use for these goods to circumvent the non-use of the sign requirement under EU law. Both Banksy and Mr. M.S, who is a Director of the proprietor, made statements that the goods were created and being sold solely for this cause. Therefore, by their own words they admit that the use made of the sign was not genuine trade mark use in order to create or maintain a share of the market by commercialising goods, but only to circumvent the law.”
Indeed, Banksy himself stated that the store might be the least poetic reason to ever make some art.
Moreover, the EUIPO and Banksy have similar opinions about each other's work:
“However, the Cancellation Division cannot agree with this assertion. Banksy has chosen to remain anonymous and for the most part to paint graffiti on other people’s property without their permission rather than to paint it on canvases or his own property. He has also chosen to be very vocal regarding his disdain for intellectual property rights, although clearly his aversion for intellectual property rights does not annul any validly acquired rights to copyright or trade marks. It must be pointed out that another factor worthy of consideration is that he cannot be identified as the unquestionable owner of such works as his identity is hidden; it further cannot be established without question that the artist holds any copyrights to a graffiti. The contested EUTM was filed in order for Banksy to have legal rights over the sign as he could not rely on copyright rights, but that is not a function of a trade mark. Therefore, the filing of a trade mark cannot be used to uphold these rights which may not exist, or at least may not exist for the person claiming to own them.”
The smoke screen cast by Banksy to cover up his persona may put a bomb under his trademark portfolio (according to the counterparty's attorney...) because of the lack of intention to use with any of the other trade mark registrations and therefore, by analogy with the present case, the trademarks have been filed in bad faith.
The decision can be read here.
