What it means
Strict Enhanced Tracking Protection blocks more tracking content across sites than Standard and can cause some pages to malfunction. Turning it off for one site changes that site's exposure while leaving the global mode in place. Mozilla also supports web-compatibility exceptions for major or minor issues in certain modes. An exception is a diagnostic and operational tradeoff, not proof that the site is trustworthy.
A real-world example
An identity-provider button on one service fails under Strict. The user confirms it works with that site's shield temporarily off, then keeps a narrow exception while the rest of their browsing stays protected.
What to do
Verify the domain, reproduce the problem, test the site's shield, and restore it if the test does not help. Record and revisit any exception after browser or site updates.
The distinction that matters
Turning off a site's shield can allow its embedded trackers to load. Switching all of Firefox to Standard changes behavior on every site. A broken page is not always caused by ETP; extensions, cookies and outages must be considered before making either change. Some Firefox versions offer built-in compatibility exceptions under Strict that can repair common issues while preserving more protection than an outright shield-off decision. Test those first and remove temporary workarounds when the service improves.
Mozilla ETP site controls
