Capping congressional salary that low is a bad idea

Exactly. Giving someone immense power without giving them pay reflecting that power is just an unstable incentive for corruption.

There are some downstream effects, too. Federal law caps regular federal employee pay to formulas based on the Congressional pay, so plenty of senior managers and Ph.D.-level specialists have their pay capped because Congress hasn't given itself a raise since 2009, all while inflation has gone up by about 50% in those 16 years. It used to be that federal employees would put up with lower salaries for better job security and belief in the mission, but the current administration has basically torn down those assumptions.

In theory Congress could lift the caps on federal salaries without giving themselves a raise, but I don't think that's very likely.