STRICT Enhanced Tracking Protection enabled no longer blocking website ads

Hello Ted,

you can check the release notes for changes: firefox.com/firefox/notes and follow the links to previous versions there to verify a few releases back to see there's probably nothing related to (lowering the protections of) ETP. This is more likely to be a website change, going from one ad delivery system to someone smaller or less intrusive or local.

I can help you run several older versions in isolation if you wanted to "go back in time" to verify yourself.

I can relate to not giving third party addons full access to web content just to remove ads. I personally use a filtering DNS for similar purpose, maybe that would be an option to consider?

Greetings, jbr...

Thank you for your quick reply to my inquiry!

I though about checking out previous versions of Firefox to see if there were any changes made to ETP, but I was concerned that reverting back to a previous version of Firefox would mean that I would not receive critical security and functionality updates contained in new versions.

Your proposal to use a filtering DNS as an option interests me. What DNS provider would you recommend I try for my filtering DNS? Any guidance you can provide regarding how I can create/configure a filtering DNS that would possibly help to block ads would be greatly appreciated.

Historically, I have configured my Firefox web browser to use Cloudflare as my DNS servers, but ever since Firefox changed the Settings section, I have been unable to find where I configured my DNS servers. Based on very preliminary research, I found DNSFilter, OpenDNS, and CleanBrowsing as three filtering DNS servers but I have no personal knowledge regarding any of these three providers. Your first-hand knowledge and expertise with filtering DNS servers would be invaluable and most appreciated.

Take care...

It's nested one level deeper now (under "Advanced" panel) — I just use the giant search box and type "DNS" to filter directly to the relevant section. You can switch away from Cloudflare there using the "Custom" option, and enter any DoH endpoint in that box. I personally use the one described here: adguard-dns.io/kb/general/dns-providers/#default i.e.:

  https://dns.adguard-dns.com/dns-query

as the custom value.

As for trying older builds to verify differences, it's definitely not meant for casual use, just as a feasible test. It entails downloading the separate Firefox Nightly that comes with its own profile, which is good for trying out things, as it doesn't interfere with your normal release version and the current "daily driver" profile.

Nightlies can be used for downgrading and upgrading as necessary for investigation purposes in isolation, and you can get rid of them afterwards. Given you're on v152 I'd say trying both one cycle older and one cycle newer could give you the idea — I'd start with downloading this one:

• ftp.mozilla.org/pub/firefox/nightly/2026/04/2026-04-19-20-35-36-mozilla-central/firefox-151.0a1.en-US.win64.installer.exe

to understand if running this older version yields the results you're looking for. (You will need to set its ETP to Strict first like you're used to, as its prefs are blank slate at this point.)

To eliminate any difference related to just being Nightly, if you see a "good" result on the older one, there's also a newer one for comparison:

• ftp.mozilla.org/pub/firefox/nightly/2026/05/2026-05-28-09-04-16-mozilla-central/firefox-153.0a1.en-US.win64.installer.exe

which if there has been a behavioral change should yield "bad" results.