Start by ruling out boredom or lack of exercise - a 3-year-old lab needs serious daily activity, so make sure she's getting a solid walk or run before you leave, not just a quick bathroom break. That said, what you're describing (destructiveness + constant barking + it happening even for short absences) does sound like separation anxiety rather than just restlessness. The key difference is that anxious dogs often target exits or scratch at doors/windows, and they go into a panic pretty quickly after you leave, which matches what your neighbor's hearing. Beyond exercise, you could try leaving calming music or a Kong stuffed with treats to redirect her, but if it keeps happening, working with a trainer who specializes in anxiety might be worth it - sometimes desensitization (leaving for tiny increments and building up) combined with something like a anxiety wrap can actually help, though obviously that depends on how severe it is for her.