Actually not a bug but it's definitely not expected behavior :not a bug:

[ddovgal]

In the footer, MangaDex link shows this on hover:

 

[justforthelulz]

THE NUMBERS, MASON! WHAT DO THEY MEAN?!

 

[ddovgal]

the second item in the array is a Timestamp, but the first... don't know
UPD: the first one is some counter, it increments...

 

[BzzBzz]

shhhhhhhhhhhhhhhhhhhhhhhh
t. mod

 

[bigtiddyoneesan]

Is this something exploitable, and that's why Bzz'z CMNT stock was forcibly sold?