Carlos Sainz has identified one of the "biggest struggles" he has faced in the Ferrari SF-23 since the start of the season. It is known that the car carries over many of the same traits as last year's F1-75, with Sainz admitting that it has been tricky to follow in the 'dirty air' of another car. "I haven't done two good qualifying [sessions] yet, but the feeling with the car is okay," he told media, including RacingNews365.com . "I think the biggest struggle has been the car in dirty air, and the first stint in Bahrain and first stint in…