Not specifically since coming to power, as far as I'm aware. The AP piece which broke the story states that "officials were not authorized to discuss the matter publicly and spoke on condition of anonymity". The obvious change in circumstances that has come in recent days is the Russian State Duma's denouncement of the treaty, however.
The State Department has also been fairly non-specific on the issue, with the line from press briefings in February and May referring in general terms to Russia not being "in full compliance with the treaty", and "Russia’s continuing non-compliance with the treaty".
The 2021 Adherence to and Compliance With Arms Control, Nonproliferation, and Disarmament Agreements and Commitments report, published by the Bureau of Arms Control, Verification and Compliance doesn't make any new allegations, but does refer to the violations which triggered the US withdrawal in 2020:
In 2020, the United States continued to assess that Russia was in
violation of the Treaty on Open Skies (OST). Specifically, in 2020,
Russia remained in violation of the Treaty in the following respects:
- Section III of Annex A to the Treaty and Open Skies Consultative
Commission (OSCC) Decision 3/04 for imposing and enforcing a sublimit
of 500 kilometers over the Kaliningrad Oblast for all flights
originating out of Kubinka Open Skies Airfield (OSA).
- Article VI
of the Treaty for refusing access to observation flights within a 10
kilometer corridor along Russia’s border with the Georgian regions of
South Ossetia and Abkhazia.
It also goes into more detail about previous "conduct giving rise to compliance concerns" going back to 2010. As the state department refers to "continuing non-compliance", I think it's highly probable that this refers to the violations in this report.
It's worth noting, that while still a presidential candidate, Biden didn't challenge the allegations of Russian violations made by the Trump administration, but rather the appropriateness of withdrawal from the treaty itself:
The Trump Administration says it is withdrawing from the Treaty
because Russia is cheating. There are real concerns that Russia is not
complying fully with the Treaty. It has improperly imposed
restrictions on overflights over certain regions (Kaliningrad and the
Russian-occupied regions of Abkhazia and South Ossetia in Georgia), to
which the United States and other parties have objected. These Russian
violations should be addressed not by withdrawing from the Treaty, but
by seeking to resolve them through the Treaty’s implementation and
dispute mechanism. That is exactly how other disputes over Russian
implementation have been resolved, including altitude restrictions
Statement by Vice President Joe Biden on President Trump’s Decision to Withdraw from the Open Skies Treaty - May 22nd 2020