VAR official Paul Tierney reviewed the incident for a potential red card but determined that Everton skipper had won the ball first and that the follow-up contact was unavoidable.
However, the retired referee claimed that Tarkowski should have received a straight red card for his dreadful challenge on the Liverpool midfielder.
"This is a red-card challenge. It’s an error by the officials not to send Tarkowski off,” Webb said on Match Officials Mic'd Up.
"From the outset with this show, we’ve committed to showing good examples of VAR use and also where we don't use it in the right way, and this was one of those examples.
"The referee recognises on the field that Tarkowski plays the ball and feels that the way he does so is reckless.
“The VAR then checks that on-field decision of a yellow card and puts too much focus on the fact that Tarkowski plays the ball."