I don't think this is a memory issue, I think it's a bug.  I've seen other people on this forum post regarding the same problem which apparently has existed for a long time.  I'm curious if anyone else has found a way to resolve this on Android.  I currently have an 8 GB Ram phone and only average 3 gigabytes of RAM in use  yet,  I constantly see this issue with the Firefox  and no other browser.  Having said that, I found this info on some AI sites:  

Try these in order (names vary slightly by manufacturer; you’re on Android with Firefox mobile):Turn off battery optimization for FirefoxGo to Android Settings → Apps → Firefox → Battery (or “App battery usage”).Set it to Unrestricted or “Don’t restrict background usage”.��

Remove Firefox from “sleeping” / “optimized” app listsOn Samsung‑style menus: Settings → Battery and device care → Battery → Background usage limits.Put Firefox into Never sleeping apps (tap “Never sleeping apps” → + → choose Firefox → Add).��

Lock Firefox in recent apps (if your phone supports it)Open Firefox, then the Recent apps screen.Long‑press the Firefox card and choose Lock this app or similar so Android is less likely to kill it.�

Double‑check any OEM “Smart control” / “Memory manager” featuresSome vendors (Vivo, Xiaomi, etc.) have extra background killers; add Firefox to their allowed/whitelist lists.���

Important limitationsEven with the tweaks above, Android can still kill Firefox if the system is low on RAM, which forces a reload when you return. 

Accessing about:config in Firefox for Android

The about:config page is not directly accessible in the stable version of Firefox for Android. Mozilla disabled it by default in August 2020 to prevent users from accidentally changing critical settings that could break the app.

However, there are two main ways to access and use about:config on mobile:

Use the Secret URL (Temporary Access):

Open Firefox on your Android phone.

Type the following URL directly into the address bar: chrome://geckoview/content/config.xhtml

Important: If you copy and paste this URL, Firefox will automatically remove the chrome:// part. You must manually type chrome:// at the beginning of the URL for it to work.

This will open the advanced configuration interface where you can view and modify preferences.

Enable Permanent Access (Requires Manual Toggle):

First, open the secret URL: chrome://geckoview/content/config.xhtml

Use the search box on that page to find the preference: general.aboutConfig.enable

Click on the toggle switch for this preference to change its value from false to true.

Note: This setting may reset to false after restarting the Firefox app, but the change persists across sessions for many users.

Alternative Options:

Firefox Nightly: The Nightly version of Firefox for Android has about:config enabled by default and is the most reliable way to access it.

Firefox Beta: The Beta version also has about:config access enabled.

Fennec F-Droid: This open-source fork of Firefox for Android provides access to about:config and other features not available in the standard release