VoiceOver speech cuts off on a second when iPhone is connected to mixer

Hi all.
I have a strange issue that I've never had before.
I need to record podcasts with demonstration of different apps with VoiceOver, and recently I started to have the issue that when iPhone is connected to mixer via it's litening to 3.5 adaptor the speech of VoiceOver doesn't start from the beginning, the volume of it rases from low to high. And it sounds like you connected bluetooth headphones or speakers to iPhone. As the result the beginning of VoiceOver's phrase cuts off, like one second.
I use iOS 16.3. Is there something I can check in iOS settings?
I use iPhone 13, Yamaha AG03 mixer. There is no such problem when talking into the microphone or playing sound from other devices such as Windows machine. I've tried to change 3.5 to 3.5 minijack cable because the old one was broken anyway, but it didn't help. I might try to connect other devices to mixer, but it seems like the issue is in iOS, since it never happened before that VoiceOver speech cuts off it's first second.
Any help will be appreciated!