Website accessibility
I'm fortunate enough to not have any disabilities, however, as a software developer, I was required to work on making an app that I worked on comply with level 2 of the A11Y accessibility checklist. It wasn't until doing so that I realized that a lot of the things that you would think only mattered to people with disabilities also applied to regular users.
Things like being able to navigate the webpage with a keyboard, or having correct color contrasts require conscious dev effort to add and the results are appealing to all users.
I'd like to spend some time in the near future to work on improving the accessibility of this app. Unfortunately it sometimes falls by the wayside a bit in terms of prioritization when you have such a small dev team.