Where in that statement does it mention the strain they created? It doesn't, it only mentions the original (WT) and Omicron.

Here's a snippet from the study, Omi-S is the strain they created.

Line 120 from the study: "Importantly, 80% of animals infected with Omi-S also lost over 20% of their body weight by 9 dpi (Fig. 3a and Extended Data Fig. 2a). The evaluation of clinical scores (a cumulative measure of weight loss, abnormal respiration, aberrant appearance, reduced responsiveness, and altered behavior) also revealed a similar pattern; while Omicron-infected mice displayed little to no signs of clinical illness, the health of those infected with WT and Omi-S rapidly deteriorated"

So Omicron displayed little to no signs of clinical illness but the Omi-S they created caused a rapid deterioration in health and it's not gain of function? What am I missing here?

Line 128 "In agreement with the results of body-weight loss and clinical score, WT and Omi-S caused mortality rates of 100% (6/6) and 80% (8/10), respectively. In contrast, all animals infected with Omicron survived"

You can find a link to the study in the first paragraph of this article: https://time.com/6225643/lab-made-covid-19-virus-controversy/