It seems like using a samurai sword when a hammer is needed. But I’m open to being proven wrong.
Please allow me to try.
Without a doubt, the A-10 is a killing machine. However, it does have some limitations.
The youngest A-10 is over 35 years old. Here's a picture of the cockpit:
Often referred to as "Steam Gauges".
The A-10 has no radar, no mission computer, no sensor fusion, etc.
Its primary weapon is the GAU-8...30mm cannon. Awesome at killing tanks, however the A-10 has to get close to the target to kill it.
The problem is that tanks seldom travel alone. They are usually joined by mobile Surface to Air systems like the SA-22 Greyhound. The A-10 has no stealth and is very vulnerable to SA-22 like systems.
The F-35 is new & state-of-the-art Gen-5 aircraft. It has stealth, sensor fusion, and is able to employ the latest and greatest USAF high tech weapons.
The F-35 can fly combat missions 24/7, even in bad weather. The A-10 has limited effectiveness at night and has no ability to employ munitions in Instrument Meteorological Conditions (IMC).
While the A-10 can carry Aim-9L/M missiles for self protection, A-10 use in an Air-to-air role is severely restricted as the A-10 has no radar.
One thing the Ukraine war has shown is that drones, HIMARS, and Javelins can kill tanks and prevent a breakout. In a high tech, high threat arena, F-35 is the clear choice.