Known issues with Photo Ephemeris Web are documented here:
Google Maps rendering in Safari 16.0 and 16.1 (fixed in 16.2)
Map lines and circles may render incorrectly (jumbled up line colors and widths) when viewing Google Maps in Safari 16.0 or 16.1. There is an outstanding bug report with the Google maps team for this issue (although the root cause would appear to be a regression in Safari 16). Safari 15 is unaffected.
Fix: Update to Safari 16.2 or switch to use a different browser (e.g. Chrome).