Why does the regular expression "not see" a number with one sign?

Question

Regular Expressions

There is a text:
ago 9 minutes, 37 seconds 666,141 views
ago 9 minutes, 37 seconds 66,141 views
ago 1 hour, 10 minutes 717 views
ago 46 seconds 405 views
ago 58 seconds 8 views

There is a regular season:
https://regex101.com/r/ jmYuCb/1

Why does the regular expression not see the last line in which one character is in the number? ... Here it is actually: 8 views

Answer 1

optionality must be done through a question mark
(?<=ago).+?(?=\s+\d+(?:[,|\d+]+)?\s+views)