Hello ​@Dadoooor apologies for the late response.
Is this problem still happening?
Do you use Android Auto or Car Play in your car?
Thanks

Hello, yes, it’s still happening.

I don’t use either AA or CP, just plain old Bluetooth .

To better understand the volume decreases in your car speakers?
Thanks

Yes, that’s correct. 

Could you please check if you have the “normalise audio” option activated in your Deezer app?
 

Hi, it’s not activated.

This is a problem I also have. Whenever I connect either an iPhone or an iPad to a bluetooth speaker of any kind the bluetooth volume is always reset to 50% (in Deezer).

Same here. Glad to hear I’m not the only one. 

Hi ​@Dadoooor ​@mrmusic33 , could you please update to the latest Deezer app version 8.0.34.5 and let me know if the problem persists.
Thanks

​@Jaime.Deezer, unfortunately the problem seems to persist. Just got 50% bluetooth volume when I reconnected to my bluetooth NAD-amplifier this morning.

I have just updated deezer and tried to see if the problem persists and its still happening to me too even after the update. Please fix this its really annoying

Yes, the problem is still here for me also. 
The app has gotten so buggy over the years, for instance now, when I try to run “Flow” from long press on home icon, I get this:

Hey ​@Dadoooor ​@mrmusic33, I believe that this is now some of the iPhone/iPad/Apple devices feature when you connect the device to a bluetooth speaker/earphones to protect the users from the ‘loud’ noise/music. As I also have the volume of the music ‘reduced’ to half of the volume bar when I connect my AirPods to my iPhone 

I started to get it since I updated my iOS to the 18 version tho.

I dont get it when i connect to airpods only when i connect to car bluetooth and i kinda started to link it since i started using deezer which is like past 7 days.