How to communicate price increases to existing customers?

Yesterday, I asked how you set your pricing strategy and discounts (you had some interesting insights and experiences to share – Thank you!).

Setting prices is one thing, but what about increasing them?

Customers can be very sensitive to price changes (especially upwards).

How would you communicate price tier increases to existing customers?

Do you use any justifications? Compensations? (e.g. in the form of adding some exceptional features)

If possible, feel free to share your template on how you communicated this without losing them.