The key word is Kindle in the original text. To Kindle a fire required work and it was the only way they had to start a fire at that time. Today we have easier ways to start a fire that doesn't require work.

Shemoth (Exodus) 35:3 TS2009
[3] “Do not kindle a fire in any of your dwellings on the Sabbath day.”

https://bible.com/bible/316/exo.35.3.TS2009