Do food labels need to change immediately after a no deal Brexit?

It depends on where you are selling the product. A 21-month transitional provision to 30 September 2022 will apply for labelling changes for goods sold in GB. However, there is no transition  available for UK goods exported to the EU. There may perhaps be some initial leniency in practice but the only way to be sure of being able to place food on the EU market will be to apply the new rules immediately after the end of transition.