I think the issue with the X85 is quite straightforward and has nothing to do with branding, the timetable or any of the creature comforts onboard.

GNE ordered new buses in good faith before covid, then the pandmic hit and then the buses arrived for the X85. New buses + improved rail offer + falling passenger number probably meant the numbers didn't stack up to keep new buses on there. Repayments for vehicles didn't stop during covid after all.

Remember you usually put new buses on your busiest routes due to the higher route costings.