EI wouldn't have been required to submit or change anything if it wasn't for Brexit
EI is a UK domestic carrier and either held or holds the UK civil service contract from travel London - Belfast, so had to do some fancy footwork to keep flying, the route network out of Belfast has grown considerably to fill the gaps from Flybe.
EI also has some legacy traffic rights at Manchester which might come into play depending on the circumstances of Brexit as DUB-MAN-DUS/DUB-MAN-CPH etc.
Expect the A321NEO to make a least 1 rotation a day either domestically or to Dublin