Chrome: Version 69.0.3497.100 (Official Build) (64-bit)
Reproducible in Firefox Quantum: 62.0 (64-bit)
Bit more info (while attempting to grab the screenshot)
the text is definitely darker (it now appears as if to convey “this text was pre-populated for you!” not “DISABLED”), and clicking anywhere in the field doesn’t appear to have a reaction (the cursors remains fixed/blinking at the start of the field). From a use-case perspective, my natural first instinct is to focus the field, then press the “End” key to jump to the portion of the title that is cut off. The “Del” key similarly doesn’t respond.
If I click in the field and press the spacebar or begin typing, everything clears out and the field begins to behave again.
So, if my process is: 1. Click the field, 2. Press “End” to jump to end of the field, and then 3. Start pressing the “Del” to delete some characters…none of this works.
But! If my process is: 1. Click the field, 3. Ignore whatever’s in there already and just start typing away…this behaves as expected.
Remember! When trying to reproduce this, you must be working against a Twitter/FB card whose title/description have been prepopulated from the Meta Data. If you fill out the Twitter/FB cards first, or manage to successfully work around this (using the technique I describe above), you won’t reproduce this - everything will behave beautifully.