pgu_ Many thanks for your tip. I’d like to add that after a while, when the system files stopped growing, everything stabilized. However, during the growth period (when it overheated and the battery degraded), the system files increased by over 20 GB. Interestingly, the overheating and file growth stop when the internet (SIM or Wi-Fi) is off, but it resumed whenever connected to the internet. My system files are currently at 108 GB, as shown in the screenshot. The battery is now in fair condition since the overheating stopped. I suspect this might be in preparation for a new update.
I have also tried using various apps for clearing cache in batches, such as 1Tap Cleaner and SD Maid. whilst it managed to clear around 6 GB of cache, this haven’t resolved the main issue of the system files still taking up over 100 GB+.
If this is a hardware issue, which part of the NP2 could be causing the system files to grow?