Why does gsub in R match one character too many?

Why does gsub("^([0-9]{,5}).*","\1",paste0(1:9,collapse = "")) return [1] "123456"?

Using gsub to remove specific characters([ and ]) in R

I want to remove ‘[‘ and ‘]’ from the string.

R: Confused over r character replacement using gsub

I have lots of line fragments like this:

Confused over r character replacement using gsub

I have lots of line fragments like this: