Millie Bobby Brown's changing accent while she promoted her new underwear line has left fans stunned.

The 20-year-old Netflix star most recently took to Instagram to show off her new intimates collection as apart of her Florence by Mills fashion line. 

And while the Stranger Things actress put her trim waistline on full display in a pair of boxer shorts and a ultra-cropped T-shirt, viewers were too busy listening to the star's fluid accent. 

Fans noticed that Millie kept switching between her British and American accents - as they claimed it was due to the amount of time she had spent in the States. 

After 13 years it's no surprise that brunette beauty - who recently tied the knot with Jake Bongiovi - was losing the tone that was tying her back to her life across the pond, but people on the web still flocked to her account to share their shock. 

Millie Bobby Brown's changing accent while she promoted her new underwear line has left fans stunned

Millie Bobby Brown's changing accent while she promoted her new underwear line has left fans stunned 

The 20-year-old recently took to Instagram to show off her new intimates collection as apart of her Florence by Mills fashion line

The 20-year-old recently took to Instagram to show off her new intimates collection as apart of her Florence by Mills fashion line

In the clip, Millie gave Kim Kardashian a run for her money as she promoted her new intimates collection while sporting tiny purple boxers and a matching tee that showed off her rock-hard abs. 

She gushed about her 'seamless' and 'soft' underwear while holding up a nude thong. 

In the beginning of the video, the star's British accent was on full display but as the clip went on, it seemed to fade away - opening up room for her American one. 

People on the web flooded to the comments section to express their shock. 

One person said: 'The British and the American accent fighting each other.'

Someone else wrote: 'Right! I noticed the British accent isn't as strong as it used to be.'

Another added: 'These days I think the American is winning lol give it a year the English will be gone.'

'Well she spent about five minutes of her childhood in the UK so it's to be expected,' one person commented.

However, fans noticed that Millie was switching between British and American accents

However, fans noticed that Millie was switching between British and American accents

People on the web flooded to the comments section to express their shock

People on the web flooded to the comments section to express their shock

Millie soared to fame when she was just 12 years old when she starred in Stranger Things after she started working on the show at 10 years old.

Since then, her career has taken off along with the sci-fi drama, which is set to release its fifth and final season. 

Last month, fans got a glimpse of season five of the Netflix show after production finally reached the halfway mark.

Netflix offered fans a behind-the-scenes look into the making of the beloved sci-fi show as viewers and stars alike prepare to say goodbye to the nostalgic series.

With Millie, the returning cast includes Winona Ryder, 52; Finn Wolfhard, 22; Noah Schnapp, 19; Caleb McLaughlin, 22; Gaten Matarazzo, 21; Sadie Sink, 22; Joe Keery, 32; and Maya Hawke, 26.

The show debuted in 2016 and much of the cast were just children when the series hit Netflix.

'So I started when I was 10. I am now turning 20 years old. It feels very weird,' star Millie said as she arrived to the set.

Millie (seen in season one) soared to fame when she was just 12 years old when she starred in Stranger Things after she started working on the show at 10 years old

Millie (seen in season one) soared to fame when she was just 12 years old when she starred in Stranger Things after she started working on the show at 10 years old

Millie (seen in 2018) has been vocal about moving on from Stranger Things over the past few years

Millie (seen in 2018) has been vocal about moving on from Stranger Things over the past few years

Millie tied the knot to her husband, Jake Bongiovi - son of rocker Jon Bon Jovi, in May

Millie tied the knot to her husband, Jake Bongiovi - son of rocker Jon Bon Jovi, in May

Although the plot details have been kept under wraps, Caleb - who plays Lucas Sinclair - did share: 'We're about halfway through filming now and it's exciting, so much going on.'

And fans are in for a finale battle, as footage showed Vecna going up against Eleven again.

'If season 4 was big, season 5 definitely feels bigger,' Jamie Campbell Bower teased as he slipped into his costume - prosthetics and all.

Linda Hamilton has also joined the series, but her role is yet to be revealed after a YouTube video showed her arrival to set.

The Terminator alum shared her excitement, noting, 'I love this show so much. I really am a fan.'

Meanwhile, Millie has been vocal about moving on from Stranger Things over the past few years.

'I think I'm ready,' the British actress told Women's Wear Daily

'It's been such a huge factor in part of my life, but it's like graduating high school, it's like senior year. You're ready to go and blossom and flourish and you're grateful for the time you've had, but it's time to create your own message and live your own life.'

And that new chapter includes her husband, Jake, son of rocker Jon Bon Jovi.

The couple tied the knot in May in an intimate wedding ceremony.