Tesla is facing a battery supply issue on its Cybertruck line, according to two Cybertruck factory workers, reports the Business Insider (BI).

The two workers told BI they were notified by production supervisors that a recent three-day reduction in Cybertruck manufacturing shifts was the result of an imbalance in the production line—specifically, a lack of working batteries for the truck.

The battery issue caused the line to get "backed up" over the past week, one of the workers said.

Employees on the Cybertruck production line were told on Monday they wouldn't "need to report to work" from December 3 to December 5, according to a memo first viewed by Business Insider.

Workers were told they'd still receive eight hours of pay for each day they'd been scheduled to work. The regular schedule would resume on December 6, according to the memo.

The schedule for the line has been inconsistent since late October, five Cybertruck workers told BI, and one employee said he began looking for new jobs as a result. The employee said he was no longer working 40 hours a week.

In April, the company shortened shifts for the line, according to an internal memo viewed by BI. Over the past month, the company has further shortened shifts for some of the workflows on the Cybertruck line, three workers said.

Last December, Reuters reported that Tesla was struggling to produce the Cybertruck's 4680 battery at an industrial scale. The battery is also used for the Model Y.

One Cybertruck worker said he felt Tesla was still "working out the kinks," adding that the line had been constantly adapting to increase efficiency and the quality of the truck, including changing factory practices to address recalls.