Samsung S7 Edge sound drops with speakerphone on

I’m having trouble with the speaker on my S7 Edge. The speaker goes quiet so often when the speaker is on for a phone call, that calls are difficult to understand. I have had this issue with 0.14 Oreo, and an unofficial 0.15 Q provided by @itsclarence .

I’m experiencing the same issue, but only on the second sim (I have the dual sim model).

On the first sim, the speakerphone function works just fine. On the second sim, as soon as I enable speakerphone, I lose all sound (sound does not return if I disable the speakerphone - I have to end the call and call again, to regain sound).

Samsung galaxy S7 edge dual sim
/e/OS Q 1.4 stable but I’ve had this issue since 2019 (Speakerphone function doesn't work for second SIM)

Has anybody else experienced similar issues?

Further info - it seems to be related to the S7 edge hardware/drivers:
On Samsung S7 Edge duos, this problem persists through the /e/OS versions (even 1.5 q still has the same issue).
I just installed a Samsung S10+ dual sim with 1.5 s and the speakerphone feature works perfectly on both sims.