The arm sounds similar to mine, back in 2020.
Nerves are damaged and interfered with during the surgery.
My arm still feels weird, but better than before.
I had a good range of motion very early on. But persevere with the exercises.
Range of motion is important, particularly if having Radiotherapy.
I have attended a Lymphodema Physio and Laser therapy centre.
They have monitored my arm for Lymphodema, which I don't have as yet.
I had some Laser treatment, to aid healing, and to treat some cording I had.
All the best for the future.