[fireworks]

"I discussed this with our backend team and upon deeper investigation, we were able to confirm that there was some issue sending the notifications to your email."

Nope.

[dboreham]

Guesses 1, 2 and 3 are : their MTA's IP was black listed by a reputable mail hosting provider's spam filtering system (because they send spam).

[joemi]

That phrasing doesn't rule out an issue on your email server's end, like the email could have bounced. (Though I'm guessing that's unlikely.)

[fireworks]

Would be surprised if that was this case - vanilla GSuite setup.

[joemi]

As I said, unlikely. But not impossible. My work has a GSuite setup and we've had a few verifiable bounces over the years, though they weren't google's fault but were the fault of glitches at our DNS provider (we don't use google for DNS).