Dutchman de Vries had been under pressure for weeks after a disappointing start to his F1 career with the Italian squad.
Alongside fellow rookie Logan Sargeant, de Vries is the only driver yet to register points in 2023 as he struggled for pace compared to team-mate Yuki Tsunoda.
His cause wasn't helped by AlphaTauri underperforming with this season's AT04, which has left the team last in the constructors' championship after 10 races with just two points.
But Red Bull advisor Helmut Marko's patience with the former F2 and FE champion was wearing thin, giving de Vries repeated hints that his future was under immediate threat.
According to various media reports, including Dutch outlet De Telegraaf, AlphaTauri has now moved to replace de Vries in time for next week's Hungarian Grand Prix in Budapest.
It is not yet clear who will replace the 28-year-old at the Hungaroring, with third driver Daniel Ricciardo and Red Bull junior Liam Lawson appearing to be the two most serious candidates.
Ricciardo returned to the Red Bull family as a third driver this after losing his McLaren drive one year before the end of his contract.
The 34-year-old Australian opted to take a sabbatical to recharge his batteries after a punishing stint with the Woking team but has been keeping race ready and completed his first test with the current Red Bull RB19 on Tuesday.
AlphaTauri had previously been tipped to promote Lawson, who has had an impressive Super Formula campaign in Japan this year, but last month team boss Franz Tost suggested Ricciardo could be the team's best bet if its youngsters were not yet ready to step up.
Source: Autosport