Drawkit

Link: https://www.drawkit.io/

Undraw

Link : https://undraw.co/illustrations

Storyset

Link : https://storyset.com/

Icons8

Link : https://icons8.com/illustrations

Error404

Link : https://error404.fun/

Delesign

Link : https://delesign.com/free-designs/graphics/

Brooklyn

Link : https://www.streamlinehq.com/illustrations/brooklyn

Blush Design

Link : https://blush.design/fr

Control Rocks

Link : https://control.rocks/

If you know other illustrations resouces, I would be happy to hear it. 😊