The 140 byte limit actually didn't last very long, it was 140 Unicode
code points since at least a decade ago. You could use 140 CJK (Chinese/Japanese/Korean) characters or 140 emojis, and if it didn't fit in an SMS they just sent a link to the tweet.
Interestingly when they doubled the character limit they also started double counting CJK characters so the limit is still effectively 140 for those languages.