I've had this problem since I first installed the game about a year ago. The idea is that the sounds of towers hitting, enemies entering the base, the miner finding an item, etc. - they all come with a delay. That is, if I turn the speed up to 3, I can already finish the game - and the sounds of the already completed game will haunt me for some time. They even cut into the commercials that you watch to get a bonus after completing a stage.
This funny bug appeared for me both then and now (I recently updated to latest version to play).

My phone is Xiaomi Mi9 SE, Android 11 with the latest firmware Miu Global 12.
Before that, there was the previous Miu Global 11 - the bug was present.

P.S. Thank you very much for the game! The best TD for a phone in my opinion