Follow-up: i turned on php debugging and got these on the page with the form:
Deprecated: Return type of Groundhogg\Form\Posted_Data::offsetExists($offset) should either be compatible with ArrayAccess::offsetExists(mixed $offset): bool, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/customer/www/staging38.construction-english.com/public_html/wp-content/plugins/groundhogg/includes/form/form-v2.php on line 2048
Deprecated: Return type of Groundhogg\Form\Posted_Data::offsetGet($offset) should either be compatible with ArrayAccess::offsetGet(mixed $offset): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/customer/www/staging38.construction-english.com/public_html/wp-content/plugins/groundhogg/includes/form/form-v2.php on line 2052
Deprecated: Return type of Groundhogg\Form\Posted_Data::offsetSet($offset, $value) should either be compatible with ArrayAccess::offsetSet(mixed $offset, mixed $value): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/customer/www/staging38.construction-english.com/public_html/wp-content/plugins/groundhogg/includes/form/form-v2.php on line 2056
Deprecated: Return type of Groundhogg\Form\Posted_Data::offsetUnset($offset) should either be compatible with ArrayAccess::offsetUnset(mixed $offset): void, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/customer/www/staging38.construction-english.com/public_html/wp-content/plugins/groundhogg/includes/form/form-v2.php on line 2060
Deprecated: Return type of Groundhogg\Form\Posted_Data::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /home/customer/www/staging38.construction-english.com/public_html/wp-content/plugins/groundhogg/includes/form/form-v2.php on line 2064