lstelie

This plugin is devoted to weblogs several years old. Visitors comming through search engines can land on a post that is several years old. 
Old posts were very likely great by the time they were poublished, but can be out of date or even wrong by the time they are read several years later. 
As a lot of people don’t read the post date, this plug in alert them that the post is old. 
wp-oldpost is a good complement to plugins like “related post”, “archives” and so on. 
In its current form the plugin is very rough, no admin, fix periods (one year/more than 6 months)…

WP OldPost

Visitors to your site are noticed if the post is old, and are invited to use either archives or the search function.

MacSteini

Many users still browse with outdated browsers, often unaware of the risks. Upgrading ensures better security and reliability. This plugin displays a subtle notification prompting visitors to update their browser. Activate the plugin, and it works seamlessly.
Visit <a href="https://browserupdate.org/" rel="nofollow ugc">browserupdate.org</a> for more details.
Want to help translate this plugin? Visit the <a href="https://translate.wordpress.org/projects/wp-plugins/wp-browser-update" rel="nofollow ugc">WordPress Translation Project</a>.
<h3>Important Notice</h3>
Breaking Changes in Version 5.0 
– Requires PHP 7.4 or newer. 
– Ensure your hosting is updated to PHP 7.4 before upgrading to version 5.0 or newer. 
– Servers running older PHP versions are no longer supported. 
 – If your server is running an earlier PHP version, please download <a href="https://downloads.wordpress.org/plugin/wp-browser-update.4.8.1.zip" title="Download WP BrowserUpdate from WordPress.org" rel="nofollow ugc">version 4.8.1</a>.

WP BrowserUpdate

Used for a client who had this exact request. Worked well.

Works as expected

This plugin notifies website visitors to update their outdated browser in a non-intrusive way.

WP OldPost vs WP BrowserUpdate