When Google Domains was wound down, its registrations were migrated to Squarespace, so many people now edit DNS in Squarespace's domains dashboard for domains they originally bought from Google. The propagation behaviour is ordinary: records carry a TTL (frequently about an hour), and resolvers serve the cached value until it expires, so a typical A, CNAME, or TXT edit is live within a few minutes to a few hours depending on where each resolver stood in its cache cycle.
As with any registrar, the slow change is repointing nameservers — for instance delegating the domain to an external DNS provider or connecting it to a site hosted elsewhere. That delegation is cached at the TLD level and can take up to 24 to 48 hours. If you migrated from Google Domains and are connecting the domain to a non-Squarespace site, double-check whether you are editing records at Squarespace or delegating away, because the two paths propagate on very different timelines.
If a change is not appearing, confirm you are editing the domain in the right place. Post-migration, some accounts have the domain under Squarespace while DNS is still expected at another host, and that mismatch masquerades as slow propagation. Querying the live nameservers first clears that up before you start counting hours.