I thought that a gmail account is used to send mail in the store and that's why you wanted to change the “from” field in phpMailer.
A common cause of non-delivery of email is the misconfiguration of the DNS zone of the domain from which we send emails. Missing records: dkim, spf, dmarc.
Check your domain to see if it is configured correctly: https://mxtoolbox.com/domain/
You can also check if, due to spam, the domain has been added to some RBL lists: https://www.anti-abuse.org/multi-rbl-check/