I had the exact same issue. I couldn’t find a definite solution to the problem. I ran a diagnostic when I got the emergency mode terminal and realized that fsck failed with error code 4. So I realized it was a problem with the microSD card. I put it into my laptop to try and format it but it was giving me an error there too. Googled those errors and tried a couple of commands to fix it but it just didn’t happen. Luckily the card was just 8 days old and I could return it for a free replacement.
The most relevant reason for this problem that I could find after a lot of research online is that this problem could be caused due to the Pi shutting down randomly due to power cuts (this could be a major and recurring problem in a country like India) Again, it isn’t confirmed that this is the cause of the problem. But I believe it is the most likely. Mine was a SanDisk class 10 UHS-I card.
Hope this helps you.