Whatsapp audio

Hello there. I’m lately having an issue with whatsapp audio messages on my iPhone 12 pro. When i play any audio on loud speaker it starts normally but when i lock the screen, or the screen lock itself after some time, the audio does a crackling sound and gets silent, when i unlock the phone then audio comes back again but i actually realised that i keeps playing even with the screen locked but it’s just silent. I also tried to get my ear close to the capsule when this happens but there’s no audio coming from there so it’s not a proximity sensor problem. This started before updating to 14.5 and even after the update it’s still happening. Tried on different iphones and other phones but the WhatsApp audios keep going even after locking the screen. Any help please??