The manufacturer of Mounjaro, Lilly, has done further testing on the batch of the 2.5mg dose you received and has extended its shelf life. A letter should have been included in your order, apologies if it was not. You can read the letter from the manufacturer here:
​https://assets.publishing.service.gov.uk/media/665700c9d470e3279dd33315/4_Mounjaro_to_publish.pdf