Burger King and Tim Hortons are experiencing staffing issues, and the Delta variation is keeping coffee-loving office workers at home, forcing parent company Restaurant Brands International to miss revenue projections on Monday.

McDonald's and Wendy's both increased their marketing and launched new menu items, putting pressure on Restaurant Brands.

In other places, COVID-19 contributed to labor issues, resulting in restricted working hours and service modes at select restaurants, as well as supply chain concerns, according to Restaurant Brands.

Burger King, like most of its competitors, has struggled to staff its outlets, with its newly launched hand-breaded chicken sandwich regarded as a labor-intensive offering.Burger Wars: How Burger King Is Taunting Its Biggest Rival Again

Analysts have criticized the marketing of various Burger King items, citing the brand as the biggest drag on Restaurant Brands' overall performance.

On Monday, Restaurant Brands said it planned to continue investing in its digital and marketing capabilities, citing a pandemic-driven shift to online orders as an example.

In the quarter ending Sept. 30, total sales increased to $1.50 billion, up from $1.34 billion a year earlier. According to Refinitiv's IBES data, revenue was anticipated to be $1.53 billion.

From $145 million, or 47 cents per share, a year ago, net income attributable to common shareholders increased to $221 million, or 70 cents per share.

It earned 76 cents per share excluding items, exceeding projections of 74 cents.