Apple's dedicated ad agency is cutting staff.

Media Arts Lab, a unit within Omnicom Group agency TBWA that's dedicated to Apple advertising, laid off several staffers Monday. The company wouldn't say how many were laid off, but a report from Bloomberg, which first broke the news, placed the number at 50.

"Yesterday was a difficult day, as we had to part with some of our talented colleagues," a TBWA/Media Arts Lab spokeswoman said in a statement to CNBC Tuesday. "Our relationship with Apple has never been stronger, but as the needs of our client continue to evolve, we must adapt and continue to evolve the composition of our teams. Decisions like this are never easy, nor are they taken lightly, but unfortunately it is the nature of the advertising business. We are incredibly grateful for the many contributions of those who are leaving us and the impact they have made at MAL and on the work."

Apple has a decades-long relationship with Omnicom Group agency TBWA, the agency behind the iconic "1984" commercial, which introduced Apple's first personal Macintosh, and "Think Different." In 2006, TBWA created TBWA/Media Arts Lab as Apple's bespoke creative agency. Lee Clow, the founder of Media Arts Lab and a close friend of Steve Jobs, officially retired earlier this year.

Meanwhile, Apple's often lauded in-house creative operations group has been adding to its ranks. The company hired Nick Law, chief creative at Publicis Groupe and creative superstar, several months ago. According to Law's LinkedIn profile, he now serves as a vice president of "Marcom Integration" at the company. Tor Myhren, VP of marketing and communications at Apple, joined from WPP's Grey back in 2016. Apple recently hired Evelyn Neill, previously of TBWA/Chiat/Day, according to her LinkedIn profile.

Myhren, in an emailed statement, said Apple has asked its agency to "evolve" as it changes its own marketing approach.

"Apple's confidence and trust in MAL as our singular ad agency is a strong as it's ever been. As we continue to evolve our marketing approach, we've asked MAL to do the same," he said.

The shift comes as Apple is marketing a slew of new products and services, from Apple TV+ to its new branded credit card. Earlier this year, Media Arts Lab hired new executive creative directors for the agency's Los Angeles headquarters to oversee creative for the iPhone and for services including work for Apple TV+, Apple Music and Apple Pay, Adweek reported in May.

Apple began building out its in-house shop in earnest several years ago, part of a broader trend of marketers taking certain advertising functions in-house to regain control or save money.

"[Media Arts Lab] is competing now with one of the best agencies in the business, and that's the in-house agency of Apple," said Avi Dan, founder and CEO of Avidan Strategies. He added that by marketing a widening array of products and expansion areas, the company might be seeking more intricate creative operations and relying more on internal resources to do that.

Greg Paull, principal and co-founder at consultancy R3, said the push and pull of creative work between Apple's in-house operations and its dedicated agency aren't necessarily new.

"The pendulum has always been swinging between Media Arts Lab and Apple for many years. The agency is a little at the mercy of Apple's whims and directions," he said.

But while brands seeking the success of Apple's in-house agency might be inspired by its results, Paull says one difference is the people Apple has inside it.

"The difference between everyone else's in-house agency and Apple's in-house agency is talent - the world's best are attracted to Cupertino and it makes it easier to develop big ideas in-house."