Hello aibd,
as I pointed out here High-pitched voices with Skype 8.110 on FP4 with /e/OS 1.18 switching to mono didn’t help me when I tried it.
I could try it again since that was a while ago and and now I have different /e/OS and Skype versions with respect to when I first tried (see here https://gitlab.e.foundation/e/backlog/-/issues/7790) but I am skeptical since I imagine that Skype should work straight away like it happens for instance with WhatsApp on my FP4.
Thanks again