These questions were asked in the context of immigration levels at that time -- and at the start of a presidential term. (Clinton's first term started in 1993, and Trump's term started in 2017.)
People in 1993 thought the Bill Clinton campaign, along with previous administrations had allowed too much immigration. While Clinton did campaign against illegal immigration, his thoughts on legal immigration were that "We are richer for the energy and ideas of immigrants."
Donald Trump was strongly anti-immigration in his 2016 campaign rhetoric. He strongly opposed both legal and illegal immigration. He opposed Deferred Action for Childhood Arrivals (DACA), which most Americans support. The sharp uptick in 2017 was a message that some people thought the Trump administration would be sending the country on the wrong trajectory with regard to immigration.
People are more tolerant of immigration during good economic times when they don't feel that their jobs or their children's jobs are threatened by immigration, while they're less tolerant of immigration during bad economic times when they fear their jobs might be threatened by immigration.
People felt threatened by immigration in the late 1980s / early 1990s. The US had just started coming out of a recession. (James Carville used the famous phrase "It's the economy, stupid" in the buildup to the 1992 election.) On the other hand, the country had seen seven straight years of economic growth by the time Donald Trump became President in 2017. People didn't feel as threatened by immigration in 2017 as they did in 1993.