The EU keeps attacking the UK through petty vindictive actions like this.
The EU spokesperson clearly knew using Las Malvinas would be perceived as support of Argentina's claim to the island which would upset the UK.
He justified it as the UK isn't a member any longer, so no one was there to object. However in Geopolitics the point of statements is to send a message to the world stage and they knew it would upset the UK.
Considering none of the Islanders want to to be Argentinian and "winning" would be subjugation and possibly genocide of its people. Someone really should point out to Germans and East European's that in their zeal to punish the UK, their leaders have directly endorsed such actions