It is a part of the program. If for instance you selected 20 tile points, you can select 20 tile points again to use through 2024. I selected the 20 tiles one twice which generated 40 extra tiles which then put the total over 100 tiles which opened up another perk to choose 15,000 bonus points. It is a bit unclear though if you don't select the same one twice, I would assume the 20 tile points stay and the new one is selected--though the wording seems to indicate the first one is taken away.
If I read you correctly, if I have 31 tiles and select the 20 tile bonus, I will then become Mosaic 1 for 2024. Is that right?