The 26-year-old is currently sidelined with a thigh injury and is expected to undergo surgery next week, potentially ruling him out for the rest of the season.
Joelinton was recently labelled as a "huge" player for manager Eddie Howe, who has transformed him into all-round midfielder having previously operated as a forward.
Howe is believed to be determined to keep hold of Joelinton, but the Daily Mail reports that Newcastle could sell the Brazil international due to a wage dispute.
Joelinton, who has contributed with three goals and four assists in 23 games so far this season, signed a six-year contract when he moved to St James' Park from Hoffenheim for a reported £40m in 2019, and his deal now has just 18 months left to run.
It is understood that Joelinton's current wage demands, which would make him Newcastle's highest earner, are beyond what the club's hierarchy are prepared to pay.
Both parties remain in talks over a new long-term contract, but they are said to be far apart on numbers at present, and if a compromise cannot be reached, then the Magpies will be forced to sell the midfielder this summer.
Joelinton could therefore have already played his final game for Newcastle if his injury indeed rules him out for the rest of the 2023-24 campaign.
Speculation over Joelinton's future comes at a time when Newcastle are having to work within the constraints of Financial Fair Play and the Premier League's Profit and Sustainability Rules.
The Magpies recently announced pre-tax losses of £73m for the financial year, and CEO Darren Eales has admitted that some first-team players may be sold to ensure they abide financial rules.
As well as Joelinton, fellow Brazilian Bruno Guimaraes has been linked with a big-money exit from St James' Park amid interest from a number of top European clubs including Barcelona, Real Madrid and Paris Saint-Germain.
Howe has insisted that Newcastle 'are not shutting the door' on potential incoming in January, with midfielder reinforcements believed to be high on the club's agenda.
The Magpies have allegedly expressed their interest in Manchester City's Kalvin Phillips, but the £7m loan fee that the Premier League champions are demanding could prove to be a major stumbling block.
The Daily Mail claims that Bournemouth's Philip Billing, who Howe signed for the Cherries in 2019, is another name on Newcastle's radar along with Middlesbrough's Hayden Hackney, who was scouted in the EFL Cup semi-final clash with Chelsea last week.
Atalanta BC's Ederson and Everton's Amadou Onana are two more midfielders that have recently emerged as potential targets for Newcastle.