the.com/unappreciation

means The failure to recognize or value something good — effort, kindness, or quality that gets overlooked instead of acknowledged.

from Built from un- (not) plus appreciation, itself from Latin appretiare, 'to set a price on' — from ad- (to) and pretium (price, value). The root sense was literally about assessing worth; over time 'appreciate' stretched from pricing goods to recognizing value of any kind, emotional or otherwise. 'Unappreciation' is simply the negation bolted on, a straightforward later formation naming the absence of that recognition rather than inheriting any colorful story of its own.