It can also misbehave without any hardware bugs due to glitching. Rates of incidence of this must be quite low or that would be considered a HW bug, but it's never zero. Run code for enough hours on enough machines collecting stack traces or core dumps on crashes and you will notice that there's a low base rate of failures that make absolutely no sense. (E.g. a null pointer dereference literally right after a successful non-null pointer check 2 instructions above it in the disassembly.)
You will also notice that many machines in a big fleet that log such errors do so exactly once and never again, but some reoccur several times and have a noticeably elevated failure rate even though they're running the exact same code as everyone else. This too is normal. These machines are, due to manufacturing variation on the CPU, RAM, or whatever, much glitchier than the baseline. Once you've identified such a machine, you will want to replace it before it causes any persistent data corruption, not just transient crashes or glitches.
I would assume that _any_ software, formally verified or not, could fail due to a hardware problem. A cosmic ray could flip a bit in a CPU register. The chances of that happening, and that effecting anything in any meaningful way is probably astronomically low. We probably have thousands of hardware failures every day and don't notice them. This is why I think rust in a kernel is probably a bad idea if it doesn't change from the default 'panic on error'.
I would assume that software can always fail in the event of a bug in the hardware. That's why systems that are really redundant, for instance flight control computers, have several computers that have to form a consensus of sorts.
It doesn't even need a bug in the hardware; cosmic rays or alpha particles can also cause the same type of issue. For those, making systems redundant is indeed a good solution.
For the situation of an actual (consistent) hardware bug, redundancy wouldn't help… the redundant system would have the same bug. Redundancy only helps for random-style issues. (Which, to be fair, the one we're talking about here seems to be.)
That's why some redundant systems use alternative implementations for the parallel paths. Less likely that a hardware bug will manifest the same way in all implementations.
