My laptop’s HDD is failing, it shows a bunch of signs such as slow file manipulation and clicking sounds. The Linux btrfs partition keeps going into read-only mode to prevent further damage, makes sense, but the windows partition is working fine (for now).
Shouldn’t harddrive failure be evident on all partitions?
If the disc is failing, it’s failing and needs to be replaced. Any in between state or partial functionality will be for a very limited time, where complete failure will strike you when most inconvenient.
Other comments address this well, but for completeness sake, you can see different failure modes on different partitions because the software that manages those filesystems is different. Very careful designs will be quick to sound the alarm, whereas dumb designs will keep on working just fine until something critical is corrupted and it fails in spectacular fashion.