The sudden upsurge of formal but unpublicized complaints about Soviet conduct now being conveyed by President Carter's top diplomatic officials to Ambassador Anatoliy Dobrynin reveals a startling change in Jimmy Carter that was unimaginable a few months ago.

The president is no longer a convinced partism of the view that Russia, like his own United States, plays politics by a set of loose but roughly definable superpower rules.

The latest evidence of this change is a request for "clarification" of the Kremlin's stunning, still unannounced incursion into Afghanistan by at least one and probably two battalions of organized military units. The use of these troops, belonging to a crack Soviet airborne division, marks the first time since World War II that Moscow has intervened in a Third World country with organized-units under Soviet command, and Carter is demanding an explanaton.

Carter's growing disillusion with the Russians also expressed itself in a private complaint direct from Secretary of State Cyrus Vance to Dobrynin on Dec.6. Vance was angry over evidence of new Soviet nuclear test ban cheating.

Lumped with Carter's dismay over earlier Soviet rule-breaking, such as its outrageous radio campaign to incite violence against Americans in Iran and its interference with food supplies to starving Cambodians, these now signals of presidential anger hint that Carter might actually -- and belatedly -- be running out of patience.

Carter is reported by White House-insiders to have been mightily buoyed up by popular acclaim for his handling of the Iran crisis. These intimates believe the president's new show of relative realism toward Moscow's superpower rule-breaking has a psychological root in his spectacular climb in the polls. This reinforces his desenchantment over growing Soviet truculence in doing what it wants, whatever various treaties and rules of conduct say.

Vance's confrontation with Dobrynin on Dec. 6 was long overdue, considering unambiguous evidence of repeated Soviet violations of the 1974 Threshold Test Ban Treaty. This sets a 150-kiloton limit on underground nuclear tests.

The United States has obtained "hard" information that the Soviets exploded two underground tests this year not yet reported by the Carter administration. It was those two tests -- each with an explosive force of between 180 and 210 kilotons -- that Vance wanted Dobrynin to explain. Dobrynin predictably denied there had been any violation.

That failed to satisfy Vance. He called on Dobrynin to supply U.S. scientist with the full geologic data on rock formations surrounding the test site and with geographic coordinates so they could more precisely measure the site of the two unannounced blasts.

At least one additional 1979 underground test is known to have exceeded the 150-kiloton legal limit (by at least 50 percent). Three 1978 explosions also broke the ceiling. Yet, until Carter ordered Vance to lodge his formal complaint, nothing whatever had been said to the Russians. The American people have never been told.

The TTBT is only one of three treaties that U.S. intelligence agencies have told Carter the Russians have broken. One of these, as we have reported previously, is the 1963 Atmospheric Test Ban Treaty, systematically violated in 1978 and once again this year, on Oct.19, when an underground test "vented" its fallout into the atmnosphere through carelessness.

The third treaty that is now the target of a formal Carter administration charge of violation is the anti-ballistic missile agreement. Despite the specific provision, in Article 6 of that treaty, which forbids antiaircraft radar to be used to track incoming ballistic missiles (rather than airplanes), the United States charged a possible violation by the Soviets last October, at the height of the crisis over Soviet combat troops in Cuba. The radars used were the most modern model associated with SAM10 antiaircraft missiles.

Yet last July, when U.S. intelligence first reported Soviet testing of SAM10 radars at Sary-Shagan in central Russia to track incoming ballastic missiles, not a word about violations was said to the Russians. Thatt failure infuriated defense-oriented senators who know about the Soviet maneuver, including Republican Sens. John Tower, Gordon Humphrey and other members of the Armed Services Committee. They are now lobbying Carter to make a diplomatic issue of the violations and let the American people in on this secret: the Russians have been playing fast and loose with vital treaties on which the future security of both countries could depend.

Whether or not Carter takes that advice, his transformation from a believer in Soviet good intentions to a chastened skeptic, while leaving room for further growth, is a healthy sign of political maturity that fits well with his new showing in the polls.