Deprecated: notices all over in admin

[roughpixels]

This has been going on for the last couple of versions. I develop themes with XAMPP locally and when I install a fresh copy of WordPress (eg: 6.1 now), then turn on debug, I get inundated with "Deprecated:" notices. For example, fresh install, go to Plugins, and you might see them (see screenshot); install and activate a plugin, such as Classic Editor...sometimes the notices disappear after several refreshes.

I get these notices all the time with debugging on, which makes it difficult to test/debug themes.

Examples:

Deprecated: Return type of Requests_Cookie_Jar::offsetExists($key) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in D:\...\wp-includes\Requests\Cookie\Jar.php on line 63

Deprecated: Return type of Requests_Cookie_Jar::offsetGet($key) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in D:\...\wp-includes\Requests\Cookie\Jar.php on line 73

[roughpixels]

showing a few of many depreciated notices on a fresh install of WP with debug on. Shows the add new plugin screen.

[TimothyBlynJacobs]

Welcome to trac @roughpixels!

We're currently tracking this issue in #54504, so I'm going to close this issue as a duplicate to keep the discussion all in one place.