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 4th
tone and is pronounced yào
, but in some contexts, especially certain compound verbs, it's pronounced yāo
tone. (The only example I know off the top of my head is 要求 yāoqiú
'to request'). I recommend ignoring the 1st
tone pronunciation for now and just recording the 4th
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
Also: thanks, Yasna!