How to fix quiet AirPods issue while sharing audio on iPhone 14 Pro Max?

Once devices are shared, the audio is controlled for each device separately within AIRPLAY controls or the control center of the iPhone doing the sharing. The control center method is explained in this article ...

Share audio with AirPods and Beats headphones from iPhone or iPad - Apple Support

Go to section "Change the volume or noise control modes".

If you stay in ... or go back to ... AirPlay, you will also see separate sliders for each device.

I have the same problem. Several years ago it used to be great, we could dance and both, two sets of AirPods worked at same volume. We could dance without disturbing the neighbors. Now it's totally useless. We ended up purchasing another set of AirPods, we will now return. Same problem. The shared AirPods is 30% lower in volume, no matter what you do, turn off noise canceling, spatial off, turn up the other volume of shared to max. We have the "Headphone Safety" Off, All firmware is current on the AirPods sets. Volume still way lower than the other set. It's like the software has told the shared AirPods to cut its power output, bass is substantially lower also. Why in the world would you not fix this. It was such a great feature before. Please FIX!! We have 3rd Gen and 2nd Gen Pro. We just purchased another 3rd gen, same problem (returning them).

I have the same with AirPod max and AirPod pro but with AirPod max and AirPod 1 generation it works…I thin the problem happen after the new software update before was working smoothly

This no longer works, because Apple - as usual - has completely changed the options in the settings menu, without updating their support pages. Every update to my phone breaks something new, and every update hides a menu everyone uses. Infuriating.

The promoted fix for this no longer works, because Apple again completely changed their setting menu.