Notes:

• The dynamic font scaling was updated in one of the loading state patches (https://gerrit.wikimedia.org/r/c/mediawiki/extensions/ReaderExperiments/+/1286456/1/resources/experiments/shareHighlight/components/QuoteCard.vue), and backported on May 13th (https://gerrit.wikimedia.org/r/c/mediawiki/extensions/ReaderExperiments/+/1286456), so it didn't land in production yet.
• Dynamic font scaling: The current implementation uses a character count heuristic to adjust font sizes. While the approach is lightweight for an experiment, it doesn't provide a guaranteed safeguard against truncation because it fails to account for rendered line height, container width, or character width. Text can be truncated at the large or medium font size if 7 lines at that size isn't enough space.
• Current logic:
  • Text with more than 400 characters is size small (0.875rem). The minimum font size is 14px.
  • Text with more than 300 characters is size medium (1rem)
  • Text with more than 0 characters is size x-large (1.25rem). This should probably change from x-large to large (1.125rem).
• To improve the current code and ensure a minimum font size then truncate approach, we'd need JavaScript to detect overflow (scrollHeight > clientHeight) at the current font size, then decrease the font, and only truncate at the smallest size.
• Next step is to check on production wiki and decide if the current approach is good enough. Otherwise, implement the JavaScript approach.

@JScherer-WMF Talked about this and we've decided that it was not pervasive enough to be an issue. Proposing to close this.