Merriam-Webster offers "cessation" as one of the meanings of the noun offset.
“Offset.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/offset. Accessed 29 Apr. 2024.
It is a specialized scientific use of the word that would trip up many readers.
The brain response to sudden onsets has been extensively studied... In contrast to this wealth of knowledge, the brain responses to abrupt and unexpected offsets have been investigated far less. The imbalance between studies of neural responses to onsets and offsets is surprising, given that offsets can also reflect environmental events demanding swift and potentially life-saving behavioral responses: for example, the sudden dimming of light intensity can reflect a predating hawk (and in fact triggers freezing behavior in chicks; Hébert et al. 2019). Accordingly, one might hypothesize that the brain responses to both onsets and offsets reflect the functioning of a common neural system devoted to the detection of, and appropriate reaction to, abrupt intensity changes of any kind (i.e., regardless of their direction or the sensory modality in which they occur). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9113248/
P.S. There the word "direction" is being used as a proxy for a physical scale that corresponds to intensity of the stimulus, from 0 to some maximum. Moving leftward (or downward) on the axis towards zero is to move in the offset "direction". Grammarians do the same sort of thing when they talk about "left" and "right" in respect to an utterance.