I don't think VAR can just overturn a penalty call without the ref going to the monitor to confirm. It's what Dyche was correctly moaning about afterwards regarding VAR, if a decision needs overturning just tell the ref rather than waste more time.
There really shouldn't be any decision where a ref needs to go to a monitor, if it's a subjective debatable call then just go with the onfield decision, whereas when a ref goes to the monitor in these cases (e.g. the Rashford red recently) 99% they overturn their original decision because they are now under pressure to agree with the VAR which then just creates more debate and anger amongst players, managers, fans and pundits alike. If it's clear and fecking obvious then just tell the ref ffs. They're just not doing themselves any favours with the protocols.