Although it is still important you maintain your score in the final IB exams and most US universities will say “we expect you to maintain the present level of academic performance” in your acceptance letters, it is rare to hear that a US university rescinds your offer due to one or two marks off your final grades in comparison to your predicted. However, if you significantly drop from the grade you were predicted, they are within their rights to rescind your offer.
In contrast, predicted grades matter more for UK universities. When you are applying, your predicted grades need to reach the IB requirement grade for your intended major to be considered. When you get your contextual offer, the offer will likely be somewhat near your predicted grades and you will need to achieve that score in the final exams in order to enroll. For example, an offer for studying History at UCL is 38 points with total 18 points at HL. If you don’t get that, there may be some flexibility when you call the university on the day if you were close to it, but you may have to go to your Insurance choice.
Your Insurance choice is your second choice university that you put on UCAS. It has a lower conditional offer than your Firm. So, if you had Loughborough as your second choice with an offer of 35 points, then if you get 36 points you could go their instead of UCL.