Robinson was arrested in November 2024 for driving 100 miles per hour under the influence. At the time, Robinson was a member of the Los Angeles Rams.
49ers head coach Kyle Shanahan isn't hopeful that an appeal will be successful, though.
"You can always appeal it, so we'll hope for the best on that, but (three weeks) is what we're planning for," said Shanahan.
Robinson signed a two-year, $8 million deal with the Niners this past offseason and is now on his fourth team in four years.
He spent the past two seasons with the Rams, starting in all 17 games last season, posting a career-high in both receiving yards (505) and receiving touchdowns (seven).
In 2022, he played in all 17 games for the Baltimore Ravens, racking up 458 yards and two touchdowns.
The 30-year-old was selected in the fourth round of the 2016 NFL Draft by the Kansas City Chiefs, where he spent the first six seasons of his career.
Robinson has 3,013 receiving yards and 27 touchdowns over the course of his 10-year career, including a Super Bowl ring with the Chiefs in 2020.