You can now apply custom regex to both the payee and memo field before transactions are transferred to YNAB. We recommend using a regex generator, and have listed two recommendations below:
Regex settings are available under Source > Advanced > Payee/Memo regex.
For this source, we've set the payee regex to ,\s*([^,]*)
. This way, payees that look like "UselessInfo, Payee name, More useless info" will now just look like "Payee name". You can easily see how your regex settings affect transactions under Transaction > Details > Advanced. If your regex finds a match, "Regex applied" will be displayed under the payee or memo, along with the regex-cleaned text.