There is some problem in iphone with selecting Bluetooth/speaker/iphone.

In waze I saw it is speaking silently, through earpiece. Turning on bluetooth, connecting to some device then setting Waze to use the speaker helps, but once you disconnect bluetooth device or turn off bluetooth, it starts to be silent again. It can be tested in waze through settings, sound then click on “on” in the menu item otherwise you have to wait to some voice direction.

Ok, so one way to have it corrected is to connect bluetooth but force sound to speaker. Lot of google searches say you have to try fix it by accessibility touch option call redirect. It simply does not help anything.
After a while I found SIRI is also not answering loudly, it talks through earpiece silently. It is a good news as you can test the issue without Waze with native application.

And the post related to that below helped. Push the button to activate siri. Then ask to tell the current time. While it is whispering silently on the iphone earpice , push the power up button, and …. it will switch to the speaker and getting loud. After that Waze is also good, and everything seems to be find, no matter if bluetooth is on or off. It was an Iphone 15 with latest IOS as of 7/7/2025. Hope this helps.