My research so far:
- This answer by lambshaanxy states it was not possible in 2014:
you can't even walk across the Causeway now that Malaysia shifted to its new ridiculously huge and rather distant Customs building.
- The Wikipedia page on the Johor–Singapore Causeway states:
Since 26 March 2022, both countries have permitted pedestrians to walk along the Causeway by foot
- However, this Youtube video shows it was already allowed in 2018 (screenshots in case the video goes down: https://i.sstatic.net/n6vAw.jpg; https://i.sstatic.net/IxRIO.jpg)
This makes me wonder: When did it become allowed to walk across the border between Singapore and Malaysia via the Johor–Singapore Causeway?