It is possible that insulin has not been kept properly which will affect the effectiveness of the insulin although this is rare and very unlikely if it is from the same batch.
Over the last week or so, for me, I would put the change of effectiveness down to the weather. But there are many other things which can affect our blood sugars beyond insulin and food.
I notice you mention that you change your insulin pen. Is that because you are using single use pens?
I highly recommend the reusable pens. These are far more robust, the cartridges take up less space in the fridge (and luggage when travelling), if using NovoNordisk (NovoRapid, Fiasp, Levemir, Tresiba) insulin, you can get them for half units with a electronic reminder when you last took your insulin. And you create far less waste so much better for the environment.