Other person's audio cuts out when I speak

When I'm using WhatsApp or Duo or any other VoIP calling app I've found so far, the phone (OnePlus 5T) seems to apply some automatic "echo cancellation" where it cuts out the other person's call if they're on speaker, every time I speak so I can't hear myself. This persists even for a second or two after I stop speaking, and can make me miss some of what the other party is trying to say as they are effectively "muted". I've tried turning off noise cancellation in the caller app without any change, and I can't find an option in WhatsApp or Duo. I've also only been able to test with the other person on an iPhone, so it may be on their end but if so is there a solution to disable it from their side? I don't mind being able to hear myself - I use earphones. Is there a way to disable this "echo-cancellation" feature? I am rooted if necessary.