Besides the ridiculousness of producing a graph that shows the vaccine eventually creating negative protection, their own conclusions of this study (that hasn't been peer-reviewed) is:
"Background: Whether vaccine effectiveness against Coronavirus disease 2019 (Covid-19) lasts longer than 6 months is unclear."
"Collectively, there is insufficient evidence to determine vaccine effectiveness beyond 6 months."
"The effectiveness against severe illness seems to remain high through 9 months, although not for men, older frail individuals, and individuals with comorbidities."