The world's longest bridge which is a suspension bridge remains the Mackinac Bridge, at just shy of 5 miles long in total (central span of less than 3/4 mile).
The longest (entirely) suspension bridge in the world is the Kurushima Kaikyō Bridge in Japan, with a suspension length of 4,015m. But it in turn is comprised of four towers, so it is effectively two suspension bridges strung together, which is why usually length of the central span is the benchmark for "longest suspension bridge in the world" and therefore why the 1915 Çanakkale Bridge is claiming the title.
4,015m is 2.5 miles. The parent comment to you said that the 1915 Çanakkale bridge is 2.86 miles long in total. If those numbers are correct, the 1915 Çanakkale bridge would appear to be the longest suspension bridge by all measures, not just central span. I don't think it has anything to do with number of towers.
This image[1] can help give you an idea of the additional length that is added by the approach without actually being part of the suspension bridge.
[1] https://cdni0.trtworld.com/w480/h270/q75/127810_turcanakkale...