No, tone sandhi in Mandarin Chinese is actually pretty simple. The reason why this thing is happening is because Chinese characters often have more than one pronunciation. Usually, 要 has 4
th tone and is pronounced
yào, but in some contexts, especially certain compound verbs, it's pronounced
yāo with 1
st tone. (The only example I know off the top of my head is 要求
yāoqiú 'to request'). I recommend ignoring the 1
st tone pronunciation for now and just recording the 4
th tone one. In this context,
yāo doesn't make any sense, but Google Translate isn't a human and so is bad at identifying context.
In Mandarin, these are called 多音字
duōyīnzì ('many' + 'sound' + 'character'), and OldBoring has complained before that they're what makes Chinese characters so hard. This is also why, on my personal thread, I sometimes include multiple pronunciations for the same word (for example, in my last post, I noted that 坟场 'graveyard' can be pronounced either
fénchǎng or
féncháng).
Also: thanks, Yasna!