The following is the Dec. 13, 2022, Congressional Research In Focus report, Navy Next-Generation Attack Submarine (SSN[X]) Program: Background and Issues for Congress.
From the report
The Navy wants to begin procuring a new class of nuclear-powered attack submarine (SSN), called the Next-Generation Attack Submarine or SSN(X), in the mid-2030s. The SSN(X) would be the successor to the Virginia-class SSN design, which the Navy has been procuring since FY1998. The Navy’s proposed FY2023 budget...
https://news.usni.org/2022/12/14/report-to-congress-on-ssnx-next-generation-attack-submarine