Thank you, Jaka.
I investigated the model and suspected that the issue might lie in the conversion to ONNX and then to a blob, as the original model was successfully detecting targets with over 90% confidence.
Using Luxonis' BlobConverter, I experimented with different arguments and found that changing "Myriad compile params" argument to "-ip FP16" made the abnormal bounding boxes disappear. Although I had previously tried this change without success, it unexpectedly resolved the issue this time, indicating that there might have been unintentional changes or previous mistakes.
Now that the abnormal bounding boxes have disappeared and the model is detecting some targets, I will focus on the model conversion process to address the unusually low confidence levels below 50%.
Thank you so much for your valuable assistance!