DNS blocking only at 2nd request

Hi,

I’ve setup DoT via my router. I’m seeing my DNS requests of all my devices in the Teams Dashboard. I’ve also set up Policies to block malware & other security risks.
If I open https://malware.testcategory.com, at first the page loads fine. But if I refresh, the site is blocked. Any idea what could be wrong?
1st try:

2nd try:

Similarly, the 1.1.1.1/help page first loads this:

While a refresh loads this:

Any clue what’s wrong?

Thanks,
Cadish

You may need to disable / change the DoH settings in your browser. How to Enable or Disable DNS over HTTPS (DoH) in Google Chrome | Tutorials (tenforums.com)

I’m using Safari, and my DNS settings are set to my router’s default.