In the past, I've configured these on my domains (and wrote about SPF with GSuite - which was at the time, Google Apps). In the last 9 years, the rest of the DNS config has changed a lot, and as I've never had issues with mail, I never reviewed my settings. Until today.
For another reason, I checked my config on mx toolbox - and I spotted that some tuning was required.
The DNS report shows a few MX errors, and more warnings
As it happens, Google offer a similar tool for their users in their Google Apps toolbox.
It seems, that at some point the recommended record has changed from:
v=spf1 include:aspmx.googlemail.com ~allTo a different domain:
v=spf1 include:_spf.google.com ~all OK; no problem - that one's easy to fix. Setting up DKIM was easy as well, using the guidance here, and again highlighted that those records were incorrect as well. At some point a CPanel server had managed the DNS config and added it's own records!
Reminder to self - review my MX settings at least every couple of years!