Thanks! The time for which TXT records are cached is determined by their TTLs. When publishing a DNS TXT record, you can usually set the TTL to be as low as 1 minute or even less, so any changes to the content would be picked up really quickly. (https://developers.cloudflare.com/dns/manage-dns-records/ref...)
I know that it's all configurable, what I meant is that some DNS providers may apply a long TTL by default, and it may be desirable to let users of Triweb know about this possible source of confusion.
The DNS name resolution is actually not done by your system or ISP, but by a DNS over HTTPs (DoH) service (Cloudflare 1.1.1.1 resolver). Cloudflare seems to be respecting the TTL as returned by the authoritative name server for your domain, so if you are able to specify a short TTL for a TXT record in your domain control panel, any changes made to the website should be live within that time.
> so if you are able to specify a short TTL for a TXT record in your domain control panel
Triweb users are able to do that, but they don't necessarily know that they need to do that. For example, the Cloudflare DNS dashboard displays "auto" as a TTL by default, and one has no idea how many seconds "auto" is for a TXT record.