After getting the site to look exactly as it should be, the following happens after a couple of weeks on its own without any intervention from the web designer:
- Embedded YouTube videos went from rectangular (4:3) to a very large square format (1:1) for no reason.
- YouTube videos overlapped text because of aspect ratio change.
- Fonts changed from sans-serif to serif site-wide.
- Font changed from set size to illegibly super small.
- Elements created using custom CSS became broken like the custom CSS got deleted even though nothing was done with the site.
- Set padding/margins/spacing got altered on its own accord, rendering text out of alignment or symmetry.
These are some I can think of.