Webflow form timeout behavior after moving between Free, Basic, and Business plans

Webflow's form builder applies a client-side timeout of roughly 60 seconds before resetting the submission UI if no server response arrives, and there is no public API to adjust this interval. Server-side processing limits also appear to differ by plan, with Free and Basic sites showing generic errors after longer waits while CMS and Business plans behave more predictably.

Adding hCaptcha or reCAPTCHA introduces extra delay, since the verification challenge must finish before the payload is sent, effectively stretching the total submission window. There is also no documented event or callback to intercept or abort a submission mid-flight, so graceful cancellation seems to require custom code that may conflict with Webflow's iframe sandboxing or spam-protection terms.

These timeout values are not officially documented and could change in platform updates.

When migrating a form-heavy site between plans, what is the supported way to detect a timed-out submission and notify the user? Can the captcha-related delay be measured or bounded reliably? Is there any sanctioned cancellation hook, or is custom code the only option?