That pension program is fully funded into perpetuity, even though few workers pay into it any more.
The Civil Service pension program is being phased out, replaced by the Federal Employee Retirement System.
The Civil Service pension program has always run a surplus. First, the employees enrolled in it paid in a little higher contribution during their working years, and in return were offered a modestly higher pension in retirement. Secondly, Congress was not able to "borrow" against Civil Service pensions. The money was kept separated in a "lockbox" (remember Al Gore proposing to do this with Social Security?) and invested in Treasuries, where the return on investment was paid back into the program. Third, many employees paying into the program were overcharged through an accounting error. So, even though very few workers pay into it (it started to be phased out during the Reagan Administration), the trust fund is healthy and can pay off all projected costs and should end up returning money to the Treasury when the last survivors pass.
This pension plan was considered to be very safe from interference because it is the same plan Congressmen, Senators and other politicians and staff used. It was intended to be a substitute for Social Security for Federal employees. Now, since so few people still collect it, there is not a large constituency to support it.
A Federal program that works as intended, is more than fully funded, and has a shrinking user base? That makes it ripe for the plucking by anti-government MAGA crooks.
By the way, if Social Security was managed as well as the Civil Service Retirement System, it would be in great shape as well