Welcome to the forum.
No matter what the maker say, no camera are truly set and forget, there have been so many cases over the years that believing this would be naive.
So the 15 minutes or so it take to look over a 256 GB card every few months are well spent.
I always focus on first and last file in drive sessions + how ever many short stops in between, i just play a few seconds of each file i inspect, just to make sure they are not corrupted, but also that the locations are reasonable.
So for instance if you have a drive session from 2 weeks ago, but it start at your gas station and not where you live, there is something going on that for sure warrant further investigation.
If you are the same creature of habit i am, using a dashcam you will soon find you drive the same routes / streets over and over, so what i see in the first / last files in my sessions are always: Where i live - Where i shop - My favorite gas station - My favorite car wash - My mothers place - My friends place - One of my favorite pizza joints - And too rare my sisters place as she do not invite her nice big brother to dinner as often as she should.
No job as i an retired, but otherwise that would of course be on the short list of destinations.
so if the clip i inspect first and foremost are not in a know location, but maybe some ways down the street i still recognize, then there is something wrong, or as you have experienced the files cant even play ( i use pot player as the #1 software player on my PC )
In a good dashcam ( dont have to be one of the high rollers ) the memory card are almost always the weak link, it is what you should look at first if you have problems, test with software's mentioned above ( if you have a PC or MAC that is )
#2 if you have used a creative way of powering the system, this can be a build in USB ports, or some multi port charger you might have, then try the provided power source too.
It is rare i have experienced corrupted files from one of my own cameras, or for that matter heard about it in here, i think this issue are mainly a issue for cheaper models, but any camera can do it for sure..
Testing your memory card will also tell if it is fake, you be surprised how many fake a 16 GB card to be a much larger card, and it will appear fine on the PC but it will of course never be able to store the much larger fake storage capacity, so test software might say " only able to test 16 GB out of 128 GB "
O and then in my testing of the memory card, after the regular files i do some random files from where ever, in that case just so they can launch and play, no telling where it is or remembering that as it might be weeks ago, at least with the memory cards i use + the level i drive which are not much even in the none corona days.
Buying a cheap dashcam and even mid ranged ones too, can often mean there will be next to no support or updated firmware's to fix flaws, and the same go for the support where at best you will have to send your dead camera to some garage store in China.
If possible you should buy local to have local warranty standards, even if this make things a few dollars more expensive.