Allison Janney says she has 'theories' for why 'Mom' was canceled but was 'told not to express them'

• Allison Janney told CBS Sunday Morning that the cancellation of "Mom" was "a shock."
• She added that she has "theories" about why it was cancelled, but was told "not to express them."
• The CBS sitcom is coming to an end this week after eight seasons.

Allison Janney says it was "a shock" to find out in February that her hit sitcom "Mom" was coming to an end after the latest season.

During an interview with CBS on Sunday, Janney, who has played Bonnie Plunkett on the popular comedy for eight seasons, opened up about the show's cancellation.

"I have my own theories, but I have been told not to express them," Janney told CBS Sunday Morning correspondent Tracy Smith while discussing the final "Mom" season.

"But, listen, eight years is a great long run for a show," she added with a laugh.

A post shared by Allison Janney (@allisonbjanney)

"Mom," which is airing its series finale this week, centers around Bonnie's recovery from alcohol and drug use and its impact on her relationships with those around her, specifically her daughter, Christy (played by Anna Faris, who announced she was leaving the show in September and didn't appear in the eighth, and final, season).

'Mom' producers announced its cancellation earlier this year

The show had only aired about half of the episodes belonging to its eighth season when "Mom" executive producers Chuck Lorre, Gemma Baker, and Nick Bakay announced in a joint statement in February that this season would be its final run.

"From the beginning, we set out to tell stories about recovery from alcoholism and addiction that are rarely portrayed in a network comedy series," Lorre, Baker, and Bakay said in their joint statement about the cancellation.

"We take great pride in knowing 'Mom' has positively impacted so many lives," they added.

Janney reacted to news of the cancellation in February with an emotional Instagram post thanking the cast and crew behind "Mom," adding that working on the show had "been one of the great honors" of her life.

She also posted a video in April celebrating one of her last days on set, thanking viewers for following along for eight years.

"We had such a wonderful time making you laugh and cry on our tv journey together!" Janney wrote. "More to come❤️."

A post shared by Allison Janney (@allisonbjanney)

The official Instagram account for "Mom" commented "Perfect. " on the post featuring Janney and her costar William Fichtner (who played her onscreen love interest, Adam) in a bright-orange car.

Janney previously speculated that the show's cancellation might have been financially-motivated

Janney, who won two Emmy Awards and two Critics' Choice Awards for "Mom," told late-night host James Corden in March that she thought she'd have more time with Bonnie before having to say goodbye to the character.

"I wish we'd had at least another year for the writers to have that much time to ramp up to the ending," Janney said during an appearance on "The Late Late Show."

"We thought, 'surely, they're going to want more 'Mom' and they decided not," she continued.

Janney added: "There's so many reasons behind that. Most of them probably money."

While we (Janney included) might not know exactly why the show is ending, Janney speaks warmly about her time on "Mom."

"It's one thing to be part of a show that entertains, which in itself is a wonderful thing," Janney told Smith on Sunday.

"But to also have an impact on people who are in recovery or people who have loved ones or family members who are going through it to make recovery an approachable option," she added.