Is it a newly planted bush? Pull it up, pull all the roots and the root ball apart and make sure the roots are spread evenly into the surrounding soil. I just had to do this with 2 blueberry plants. It does look like something defoliated the stems. Blueberries are a host plant to many species of moths and butterflies, its possible some caterpillars or "worms" ate the leaves. https://www.canr.msu.edu/news/how_to_avoid_a_common_blueberry_planting_error

No had it for about a year now

I had problems with blueberries until I checked the soil pH, they like it on the acid side in the pH around 5 range. Adding granulated sulphur around the plant now should adjust the soil pH by Spring assuming that's the problem.

A less than ideal soil pH will not make all the leaves fall off :-) And blueberries tend to be far more tolerant of a higher pH than many think. They still need an acidic soil but not highly acidic. I live where blueberries are a major commercial crop and our soil pH is not overly acidic (6.0-6.3 or even slightly higher) nor do the larger growers amend routinely to make it more so.

That looks to be more like an insect issue or perhaps something with the watering....too dry or too wet. It is also important to note that most blueberries are not evergreen - they are deciduous and will drop their leaves in fall and with colder weather. Southern highbush blueberries tend to be only semi-evergreen even in very mild climates

Don't get too discouraged. these plants have just survived the brutal summer - when it seems only bugs and weeds seem to thrive.

I lost one or two blueberries this summer, but the two I have left look pretty good (so who knows? The Florida gardening guide / website will have info on blueberries.