Does anyone know if testosterone shots help or affect male fertility?

Bailey • Ava Madeline🧸 07/23/2020🌈 IVF baby

We found out my S/O has low sperm count he went to a general physician and they took his blood to test his testosterone levels and they came back low and he said his doctor is recommending Testosterone shot and it will help but online i am reading it can actually make things worse??? Is this true or should i let him get the shot I’m worried it will make everything way worse I told him we should go to a male fertility doctor and he thinks the physician knows everything.