For a PCB it’s called a rework, and it’s very common for first spins of boards to have to do one.
Also common is to patch around issues, when possible, in firmware. This is often lower cost/effort, but can’t fix everything.
There are similar kinds of fixes for purely mechanical parts. Depending on the part and problem, mechanical can be easier than a PCB rework (eg: modify a part in CAD and 3D print or get your local machine shop to do a run).
Or require a particular type of motor oil with a particular type of metal-based lubricant additive when you realise 100,000 cam shafts have shipped made of metal you’d assumed was to a higher spec but isn’t, just so the engine will make it through warranty period with insanely long service intervals.
I briefly looked at a couple used vehicles just outside of warranty and one within warranty that had literally had two oil changers in 100,000k, that’s 60,000 miles for the uninitiated.
Also common is to patch around issues, when possible, in firmware. This is often lower cost/effort, but can’t fix everything.
There are similar kinds of fixes for purely mechanical parts. Depending on the part and problem, mechanical can be easier than a PCB rework (eg: modify a part in CAD and 3D print or get your local machine shop to do a run).