https://man7.org/linux/man-pages/man5/proc_meminfo.5.html

Cached %lu

In-memory cache for files read from the disk (the page cache). Doesn’t include SwapCached.

Cached should be memory stored on HDD and not RAM.

That sounds like a memory leak.

Accidental reply

From what I understand, they (hackers) try known email/password combinations at different sites because a lot of people reuse their passwords. I also find it unlikely that anyone trying hack accounts will spend any amount of time looking at individual passwords if their list is 1000+ (and we know there are leaks in the milions).

I agree that they are reasonably save unless they are targeted.