The devices shown here are devices that have differences between the functionalities present in Gladys, and the functionalities coming from Zigbee2mqtt.
On my system, I only have 2 devices in this list (despite more than 30 Zigbee devices):
The first is rightly there because it’s an old button I no longer use and that is not in Gladys.
The second is an Aqara motion sensor that causes issues because it has a dual functionality « Decimal brightness (Luminosité décimale) », and since the fix it appears forever in this tab; this was reported recently in a bug report ( Zigbee2mqtt: Aqara motion sensor with double feature still showing in discovery like an update is available · Issue #2060 · GladysAssistant/Gladys · GitHub )
Can you tell me which devices appear?
You need to go case by case and see why these devices are not similar between Gladys and Zigbee2mqtt — nothing serious in any case, it doesn’t impair usage 
That, however, is more serious — I’d like you to create a separate topic with all the information so I can see what’s wrong