From the RFC7208:
The SPF record is expressed as a single string of text found in the RDATA
of a single DNS TXT resource record [...]
So yes, a SPF record is really just a TXT record that starts with “v=spf1”.
So some providers might refer to TXT-records which follow the SPF syntax as “SPF records”, but technically speaking, they are TXT-records (whose value follows the SPF syntax).
As to cloudflare, I would guess that adding a TXT record of “v=spf1 -all” has the same result as adding a SPF-record of “-all”?