You leave a document open, work in another tab, and return to a loading screen. The tab never disappeared, but that does not mean its page stayed active. Before changing settings, note what actually happened: a reload, missing text, or a request to sign in again. These are different observations.
Check the browser without guessing about the website
Desktop Chrome can deactivate unused tabs through Memory Saver and reload them when you return. Look in Settings, then Performance. Google's instructions for these controls concern computers, not the equivalent settings on Android or iPhone.
A reload alone does not establish that Memory Saver caused it. The page might refresh itself, or another problem may be involved. Record whether it happens only after switching away and whether Chrome marks the tab as inactive. Avoid changing several settings at once: you would lose the chance to identify which change helped.
If one site needs to remain active, inspect the site-specific exclusion under Performance. Add only the relevant site rather than every website. An exception addresses tab deactivation; it does not promise that the website will retain a draft or keep your account signed in indefinitely.
Save the work independently of the tab
Imagine drafting notes for a club meeting. Before leaving the page, use its save command and look for confirmation. For important text, keep an appropriate separate copy where you are allowed to store it. A visible tab title is not a saved version of your notes.
Test the site's behaviour with a disposable sentence, not your only copy of a long draft. Check what remains after leaving and returning, and whether the service actually saved it. Chrome may avoid deactivating partially completed forms, but that is not a backup guarantee. If you also have to sign in again, investigate the account session separately. Keep the saved text before troubleshooting either symptom.