Why is my SPF record invalid when I have both Google and Shopify in it?

Multiple separate SPF records in your DNS invalidate each other. You must combine all authorized senders into a single, unified TXT string (e.g., “v=spf1 include:_spf.google.com include:shops.shopify.com ~all”).

“This is almost always two separate SPF records fighting each other instead of being combined into one. I’ll merge them into a single valid record within 24 hours for $99.”
— Jeff Bollettino, Managing Director, Ignite Conversions