Apple Music on iPhone volume very low through Bluetooth speaker

Thanks for your reply. My Denon is pre-Bluetooth with a Bluetooth dongle, and I have the same issue with a Hive Bluetooth speaker, ie the volume will not increase beyond a much lower point than previously. It was fine until recently, which coincided with getting volume warnings on my phone as though I was using headphones. These have stopped now, at the same time as the Bluetooth volume output has decreased. I don't know whether the two are linked or whether it was just a coincidence. However both Denon and Hive work fine with my iPad so that is the easy solution. But I would like to know what the issue is with my phone. I wondered if it is anything to do with the volume limiter that it now seems impossible to disable on my phone.

Thanks so much - you nudged me into investigating Sound and Music settings properly, and I finally discovered in Headphone Safety that if you ignore headphone usage warnings eventually the volume is turned down automatically. The remedy turned out to be classifying Bluetooth devices correctly as speakers not headphones. I’m pretty sure I wouldn’t have found that out without your advice. Thanks again. : )