Pope Francis is evicting US Cardinal Raymond Burke, an outspoken critic, from his Vatican apartment and revoking his salary.
Cardinal Burke is part of a group of American conservatives who have long opposed the Pope's plans for reforming the Catholic Church.
A Vatican source told the BBC that Pope Francis has not yet carried out his intention to evict the 75-year-old.
And the decision is not meant as a personal punishment, the source added.
Instead, it comes from the belief that a person should not enjoy cardinal privileges while criticising the head of the church.
Still, the move is "unprecedented in the Francis era", Christopher White, a Vatican observer who writes for the National Catholic Reporter, told the BBC.
"Typically, retired cardinals continue to reside in Rome after stepping down from their positions, often remaining active in papal liturgies and ceremonial duties," he said. "Evicting someone from their Vatican apartment sets a new precedent."
Mr White warned that the decision could "provoke significant backlash" and deepen divides between the Vatican and the US church, where there is already "fragmentation".
Cardinal Burke has yet to respond to the news and the BBC has reached out to his office for comment.
The Pope revealed his plan to act against the cardinal at a meeting with heads of Vatican offices last week.
His frustration with US detractors who take a more traditional or conservative view on several issues appears to be coming to a boil.
Earlier this month, he fired Joseph Strickland, a conservative Texas bishop who had blasted his attempts to move the church to more liberal positions on abortion, transgender rights and same-sex marriage. The removal followed a church investigation into governance of the diocese.
A few months before, the Pope told members of the Jesuit religious order in Portugal that there was "a very strong, organised, reactionary attitude in the US church", which he called "backward", according to the Guardian.
Tensions with Cardinal Burke, who was appointed by Pope Benedict XVI, have been simmering for nearly a decade, with the American prelate openly criticising Pope Francis over both social and liturgical issues.
"Cardinal Burke's situation seems to stem from his gradual alienation from the Pope," said Mr White. "It appears the Pope perceives Burke as fostering a cult of personality, centred around traditionalism or regressive ideals. This action seems aimed at limiting Burke's influence by severing his ties to Rome."
Most recently, the cardinal held a conference called The Synodal Babel in Rome on the eve of the Pope's synod, or meeting of bishops, last month.
He also joined fellow conservatives in publishing a "declaration of truths" in 2019 that described the Catholic church as disoriented and confused under Pope Francis, saying that it had moved away from core teachings on divorce, contraception, homosexuality and gender.
Notably, he disagreed with the Pope promoting Covid vaccines.
Within church politics, he and Pope Francis were at odds over the firing of the head of the Knights of Malta after the order's charity branch was found to have distributed condoms in Myanmar.
The Pope, in turn, has demoted Cardinal Burke within the church hierarchy or moved him to posts with less influence over the years.
Michael Matt, a columnist for the right-wing Catholic newspaper The Remnant, wrote that the most recent action taken against Cardinal Burke showed that Pope Francis was "cancelling faithful prelates who offer hierarchical cover to pro-life, pro-family, pro-tradition hardliners".
He accused the Pope of putting critics into "forced isolation".