Some phones are worse than others. But most have a 200 ms lag in the audio when using bluetooth. Charts below show some examples.
I read somewhere that iPhones have 150ms bluetooth latency, but can't find the source of that measurement right now. Under 40ms is supposed to be undetectable.
Only current way to reduce that lag that I have heard, is to: 1) Separate the audio and video and then 2) Make the video lag the audio by the same amount as the bluetooth latency.
Sounds simple, but don't think any current phone or computer has this native ability. I have seen an App that does this to basically eliminate latency; But it only works withing that App, And not for anything else.
Be happy you don't have a Huawei Mate 20 Pro with 500ms of lag !