WPA2-Personal security

Nothing is broken - but your WiFi network may benefit from update in either settings or improved hardware...

Your iPad is no less secure today than it was prior to the update to iPadOS14. However, your iPad is now better able to [warn] bring to your attention security deficiencies of your WiFi network and iPad settings.

This support page will describe the more secure (recommended) settings for WiFi:

Recommended settings for Wi-Fi routers and access points – Apple Support

It is possible that your WiFi Router is too old to be (or not capable of being) configured for more secure settings. As such, you can either configure the most secure settings that your Router will support - or replace your Router with something more advanced that provides better security configuration options. 

Whilst WPA3 is the newest standard, you should aim to use WPA2 (AES-PSK) as a minimum. Some Routers seemingly continue to support the insecure/deprecated TKIP standards - even when apparently configured for WPA2 operation; TKIP will definitely cause a security warning to appear.

There is a also new privacy feature included within iOS/iPadOS14 that hides your physical MAC Address - and instead uses a randomly selected Private MAC Address. This feature can be enabled/disabled on your iPhone/iPad for each configured WiFi Network. This feature also has bearing upon the appearance of the Weak Security notifications.

More information about this new feature can be found here:

Use private Wi-Fi addresses in iOS 14, iPadOS 14 and watchOS 7 – Apple Support

If you are unable to employ more secure security settings on your WiFi network, you might consider replacement of your WiFi network equipment, such as your WiFi Router, with more advanced equipment. However, if the router is provided by your ISP, this may not be practical proposition. A potentially cheaper and more flexible approach might be to add an additional upstream WiFi Router, of WiFi Access Point (AP) that meets the required standards.

I hope this information provides some helpful insight into ways to resolve the WiFi Security warnings that you might observe after updating to iPadOS14.

Your router being set to AES doesn’t, necessarily, indicate that TKIP is disabled - and this appears to be the problem for many that report recurrence of the warning. The message is an advisory, but it only appears because there is something that your iPad has detected.

To repeat and amplify my earlier comment - your iPad is no less secure today than it was prior to the update to iPadOS14. Your WiFi network/router settings are potentially the weak link - and your iPad will generally identify and list the cause in iPad Settings.

Settings > WiFi > [Your WiFi Network / SSID] - tap the “i” icon - at the top of the page should be an explanation of the detected condition that causes the Privacy Warning.

Your iPad may also suggest that Private Addresses (a setting for iPad - not the Router) are not enabled. The link to a description of this feature is included in my earlier reply.

Seems like your Router is not actually set to AES. Or at least the particular Wi-fi connection is not set to that.

If you have a Router than has suport for 2.4ghz and 5ghz networks one of them, the one you are currently connected to, may not be set to WPA2(AES) but rather TKIP.

Double-check your router configuration.

Your iPhone, running iOS 13.x, does not feature the new security/privacy detection features of iOS/iPadOS14.

Be aware that in maintaining iOS13.x on your iPhone that you remain exposed to a number of security issues - long since patched with more recent updates.