Same is this issue: https://community.shopify.com/post/2562335
Topic summary
“Preview your theme” from shopify theme dev opens the live storefront instead of the local dev server (127.0.0.1:9292). Hot reload has stopped, and local changes don’t appear in that preview, although the Theme Editor link still functions.
Multiple developers report the issue (one on CLI v3.58.2), noting it began recently. Some can only review changes by generating a theme preview link rather than using the local dev server.
Staff guidance: contact Partner Support via the Partner Dashboard for investigation.
Workaround reported: clearing the browser’s site data/cache via DevTools > Application > “Clear site data” fixed the problem for at least one user (screenshot provided).
References: a related community thread and GitHub issue #3466 are linked.
Status: partially mitigated by cache clearing for some users; root cause not confirmed and the issue appears ongoing.