according to the function date_get_week,
a year has a week 53 only if the 31 december of this year is a thursday.
the exception is : if the 31 december is a friday AND the year is a bisextile year.
However, the friday 31.12.2100 is a friday of a bisextile year, and has only 52 weeks according to the function.
Could you explain me the point I missed in the rule ?