Tramadol vs Buprenorphine injection for chronic pain?

My dog is on hospice care and the vet has recommended Buprenorphine injections. However I’m feeling uneasy about it since he’s had negative reactions to almost every new medicine he’s tried these past few months (prednisone, diazepam , nsaid)

He doesn’t seem to have severe pain but mild-moderate pain due to dental disease and arthritis. His IVDD pain is controlled with pregabalin.

Does Buprenorphine have any severe side effect risks? I’m mostly worried about it making him agitated and worsening his CDD, or making him too sedated and wobbly. The vet said it’s safe, but I wanted more opinions 🥹

He has had tramadol shots in the past with no issues, but I recently learnt they aren’t really effective ? Is that true?