Question Approval email bounced back

I had a new family member register on the site. They also verified their email. So I then approved the account like I have always done. Except this time the email bounced back with the following message. It appears google has put new protocols in place that is causing this. Does anyone know what this means and how to rectify it? Obviously her email (I changed it to xxx below) is correct as she verified it in the registration process.

---

This is the mail system at host soproxy4.mail.unifiedlayer.com.

I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The mail system

<xxx@gmail.com>: host gmail-smtp-in.l.google.com[142.250.27.27] said:
550-5.7.26 This message does not pass authentication checks (SPF and DKIM
both 550-5.7.26 do not pass). SPF check for [markowfamily.com] does not
pass with 550-5.7.26 ip: [69.89.20.138].To best protect our users from
spam, the message 550-5.7.26 has been blocked. Please visit 550-5.7.26
support.google.com/mail/answer/81126#authentication for more 550
5.7.26 information. js19-20020a17090797d300b007ebc267e9fasi20925395ejc.83 -
gsmtp (in reply to end of DATA command)


Reporting-MTA: dns; soproxy4.mail.unifiedlayer.com
X-Postfix-Queue-ID: 96FB78033223
X-Postfix-Sender: rfc822; admin@markowfamily.com
Arrival-Date: Fri, 13 Jan 2023 00:41:29 +0000 (UTC)

Final-Recipient: rfc822; xxx@gmail.com
Original-Recipient: rfc822; xxx@gmail.com
Action: failed
Status: 5.7.26
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 This message does not pass authentication
checks (SPF and DKIM both 550-5.7.26 do not pass). SPF check for
[markowfamily.com] does not pass with 550-5.7.26 ip: [69.89.20.138].To best
protect our users from spam, the message 550-5.7.26 has been blocked.
Please visit 550-5.7.26
support.google.com/mail/answer/81126#authentication for more 550
5.7.26 information. js19-20020a17090797d300b007ebc267e9fasi20925395ejc.83 -
gsmtp

Thanks,
Doc

Your domain markowfamily.com has an SPF entry in its DNS. See mxtoolbox.com/SuperTool.aspx?action=spf%...ily.com&run=toolpage

I'm not an expert in SPF, so what follows may not be 100% correct.

The error says that Google will not deliver the mail because the SPF (or DKIM) fails.

Your SPF rule says that mail will only ever be sent from 66.147.244.88

Are you certain that your SMTP relay (soproxy4.mail.unifiedlayer.com??) has this IP address?

Has your provider changed the IP address of their mail server. I see they operate from the range 66.147.240.0/20
Perhaps use this in your SPF rule, rather than the one address?