Phonak Naída M70 - Bluetooth sound fades out and the volume comes back up approx. 30 sec

Dear everyone,

I was given a pair of Phonak Naída M70 devices, for both ears.
I’ve been wearing the devices regularly for the past few months, and I’m over the period of getting used to them.
Thanks to the helpfulness of the forum members, I managed to find a solution to a significant part of the problems I experienced earlier, and I am infinitely grateful to everyone for that.

I am currently facing a problem that I have not been able to find an answer to.
The M70 can communicate with a phone/computer via bluetooth.

When listening to music and at the beginning of streaming any movie, video or digital content, I find that it starts playing at the ideal volume, and then the volume decreases continuously. It stops at one level, and then the volume gradually returns to the initial level. The turnaround time is approx. 30 seconds, from the start of the fade to the return of the volume.

When listening to music (Spotify), it always appears only at the beginning of the music.
However, the phenomenon is common when watching movies. Especially during speech, I experience that the sound, music and all sound effects in the film come back during action or transition parts, but as soon as a new dialogue or monologue starts, the sound in the HA goes through this process of fading and then getting louder again.

Has anyone encountered this phenomenon? If so, is there a specific setting for this?