Pixel 3a XL - Echo on speakerphone ONLY on WhatsApp calls

[dnice-one]

Hi, today I installed WhatsApp on my recently purchased Pixel 3a XL (my very first Android phone as I am switching from a windows phone) only to discover that whenever I turn the speaker on during the call, the sound of the other person echoes really bad with some high frequency screeching towards the end. Echo is not as bad when I turn the volume of the speaker down but that negates the whole purpose of switching it on in the first place. Normal phone calls are ok, problem only appears during WhatsApp calls with speakerphone on.

So my question is, can this problem be fixed by tweaking some settings? I have tried but failed so far.

Thanks in advance.