Pinephone is not able to use internal speaker on phone calls

In my case Pinephone has never been able to handle a phone call through internal speaker. Instead, I must always put the phone near my ear, overheating it and my brain too. When I try to press the speaker button while on a call, it doesn't work and nothing happens. A user on matrix said that this feature works on postmarketos (but that is to verify). On telegram I can make hands-free calls without any problems. As far as I know, this could be due to the lack of noise cancellation for audio stream coming from the modem (but this is not my field). I am on Trixie, Pinephone v1.2b, modem with floss firmware.