Why did today's SAT have 5 sections?

My son took the SAT this morning and was surprised to see 5 sections. I thought the new SAT wasn’t supposed to have an experimental section. Every practice test he took on the college board website had only 4 sections.

The SAT has always had an experimental section. The practice tests on TCB’s website never includes the experimentals.

I only had 4 sections. Intl’ student.