The Media volume on my Z Flip is not near as loud when using a Bluetooth speaker as any other Samsung phone I've owned. I've connected with a couple of different speakers only to have the same result regardless of how much I increase the speaker's volume. These same speakers are extremely loud when connected to my S10+. I've investigated every setting I can find. I'm thinking this may require a software update? Anyone else having this issue?
I recommend reaching out to Premier Services they can be reached online at https://www.samsung.com/us/support/galaxy-z-premier-service/
or by phone at 1-888-970-3653