Thank you for posting your query on Microsoft Q&A, from above description I could understand that you are looking for ways to block pop-up on browser via Microsoft Intune/M365 defender.
Please do correct me if this is not the case by responding in the comments section.
You could block pop-up for native OS browser via Intune/MEM device restriction policy:
- For Windows devices we could apply this via settings catalog :
- For android devices this could be applied via browser control policy:
- Pop-ups (Samsung Knox only): Block turns on Pop-up Blocker to prevent pop-ups in the web browser. When set to Not configured (default), Intune doesn't change or update this setting. By default, the OS might allow pop-ups.
- For iOS devices this could be applied via device restriction policy too for safari:
- Block Safari Pop-ups: Yes blocks all pop-ups in the Safari web browser. When set to Not configured (default), Intune doesn't change or update this setting. By default, the OS might allow the pop-up blocker.
Please "Accept the answer" (Yes), and share your feedback if the suggestion answers you’re your query. This will help us and others in the community as well.