Since bug 1901888 the input field in the find bar (Ctrl + F) no longer has a border. Therefore, it's very difficult to see a difference between the input field and the toolbar itself. This could be considered as an a11y issue. The address has the same bad contrast since years, though. So maybe you won't consider it as an a11y problem. I decided to file it as regression because bug 1901888 only mentions Linux, it is about a textarea and not an input field, and it doesn't mention any change for the find bar at all. So it's not clear if you're aware of that side effect. Additional note: The border is missing on macOS as well, but already since Firefox 126. So for macOS there is a different cause.
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Since bug 1901888 the input field in the find bar (Ctrl + F) no longer has a border. Therefore, it's very difficult to see a difference between the input field and the toolbar itself. This could be considered as an a11y issue. The address has the same bad contrast since years, though. So maybe you won't consider it as an a11y problem. I decided to file it as regression because bug 1901888 only mentions Linux, it is about a textarea and not an input field, and it doesn't mention any change for the find bar at all. So it's not clear if you're aware of that side effect. Additional note: The border is missing on macOS as well, but already since Firefox 126. So for macOS there is a different cause (bug 1907503).