You will have to ‘translate’ the condition to DAX, so you can assign it a value for conditional formatting. See this topic to get an impression of how that could work.
If you need a pointer for the DAX logic… the important thing is to remove the Channel from the filter context in order to perform this comparison. See Accelerator W3 to learn about that.
At this time you only have 2 channels in your model - is that an accurate representation? If not, think about adding a Channel DIM table with an Index to make it easier, for example - the table below - will allow you to compare a next with a previous channel.