It's not just you.
Like Chinese, with which it has some historical connection, Vietnamese is a tonal language. And, of course, so is Thai.
It's the sing-song sound of those tones which make these languages unattractive to me, along with the high-pitched voices. Listening to it day after day is a real trial.
I wish they'd drop down an octave.
Vietnamese and Thai sound totally different to me.
BTW, no "high-pitched squealing" from me, whether I'm upright or horizontal!