Update Discarded Tab On Select v1.7
This extension is equivalent to pressing Reload (F5) on a loaded tab. Cached content may be used to display the page. This is not the same as pressing Ctrl+F5, which will bypass the cache and download all the web page content again.
This extension only works on discarded tabs with http or https URLs.
Only the web page that is displayed when the tab is selected is updated, not web pages that are accessible through the forward or back buttons.
This extension can be toggled on or off by clicking its toolbar button. Options are available by right clicking the toolbar button.
Click under 'Version History' to install this extension when using Firefox 62-87. Note that the older versions of this extension use the 'Access your data for all websites' permission.
Issues
If 'browser.sessionstore.restore_pinned_tabs_on_demand' is set to true in the about:config page, Firefox will not show pinned tabs as discarded tabs to an extension after a Firefox restart.
When last tested with Firefox 91alpha, after reloading a tab and then selecting a discarded tab with the same URL, I had to wait roughly 30 seconds after reloading before selecting the discarded tab to make it display new content.
(bug is fixed in Firefox 88) If using a tab discarding extension, note that there is a bug where Firefox may return the wrong URL for a tab discarded by an extension, if it was previously discarded. To reproduce the bug, select a discarded tab and let it load, load a URL that is different than any in the tab's history, discard the tab with an extension, and then bookmark the tab without activating it. The bookmark will show a previous URL in the tab's history. The correct URL will still load if the tab is selected, though. This extension is effected by this bug in a couple ways. The tab menu items may show the wrong URL and since this extension only monitors discarded tabs with http(s) URLs, it will ignore updating a tab that has an http(s) URL when Firefox gives this extension a non http(s) URL for the tab.