Dec UY can be tricky but the biggest piece with any UY is completely forget about calendar year
So, the 150 banked 2019 points expire at the end of your 2020 UY...November 30th, 2021.
Your 150 points can be used during your 2020 UY or banked into your 2021 UY as long as it’s done by July 31st.
And, your 150 2021 UY points can be used during the 2021 UY...which goes from Dec 1st all the way until November 30, 2022.