Google has released Chrome 89 to the stable channel and it is now closing the loophole for developers to skip the PWA Instability condition, with a warning appearing in DevTools in the issues tab, and with Lighthouse indicating an issue. Later, with Chrome 93 it will be enforced.

If your PWA already has an offline experience, you're all set. There's no action required, but, if you don't, it's time to add one!

[developer.chrome.com...]

Improving Progressive Web App offline support detection [developer.chrome.com]