What a 307 redirect means
HTTP status 307 "Temporary Redirect" works like a 302 but is stricter: the client must repeat the request to the new URL with the same method and body. A form POST stays a POST instead of being turned into a GET.
Its permanent counterpart is 308 "Permanent Redirect", which behaves like a 301 but also keeps the method. Search engines treat 307 as temporary and 308 as permanent.
The "307 Internal Redirect" you see in Chrome
If you open a site over http:// and the browser DevTools show "307 Internal Redirect" to https://, the server did not send that redirect. The browser generated it because the site uses HSTS (HTTP Strict Transport Security), so it upgrades the request to HTTPS before anything is sent.
Search engine crawlers do not see this internal 307. They still see whatever your server actually returns for the http:// URL, which should be a 301 or 308 to https://. A redirect checker shows the real server response.
Is a 307 bad for SEO?
Not when the move is temporary. Google passes signals through it and keeps the original URL indexed. Use a 301 or 308 for permanent moves such as an https migration or a new URL structure, and keep each redirect to a single hop to avoid a redirect chain.
Example
A 307 response and its permanent counterpart:
HTTP/1.1 307 Temporary Redirect
Location: https://example.com/api/v2/orders
HTTP/1.1 308 Permanent Redirect
Location: https://example.com/new-path