Those tools aren't using the macro which means they are not following the RFC, stop using crappy online tools and wasting people's time.

You can read about it here: https://datatracker.ietf.org/doc/html/rfc7208#section-7

dig +short TXT "159.112.254.142._ip.v5142.v530814cf.use4.send.mailgun.net._ehlo.upwork.com._spf.vali.email"

"v=spf1 include:mailgun.org -all"

--

dig +short TXT mailgun.org

"v=spf1 include:_spf.mailgun.org include:_spf.eu.mailgun.org -all"

--

dig +short TXT _spf.mailgun.org

"v=spf1 include:_spf1.mailgun.org include:_spf2.mailgun.org ~all"

--

dig +short TXT _spf2.mailgun.org

"v=spf1 ip4:104.130.122.0/23 ip4:146.20.112.0/26 ip4:161.38.192.0/20 ip4:143.55.224.0/21 ip4:143.55.232.0/22 ip4:159.112.240.0/20 ip4:198.244.48.0/20 ip4:204.220.168.0/21 ip4:204.220.176.0/20 ~all"

And there's 159.112.240.0/20.

--

The SPF lookup limit is 10 which means that this way of doing it is totally valid.

And here's where you can read about the lookup limit: https://datatracker.ietf.org/doc/html/rfc7208#section-4.6.4

Got it. Thanks and apologies.