Choose a fixed code when the address should stay in the pattern, or an editable code when you may want to change where it goes later.
The pattern shows up when the address is valid.
A fixed code stores the destination in the pattern, so a scan does not pass through this site. An editable code stores a short link here, so you can change the destination later. Editable codes do not expire after a few days. They keep working while this site is online.
A fixed code does not expire. The web address is in the pattern, with no trial and no account. An editable code also has no trial period. It keeps working while this site is online, and you can change the destination whenever you want.
Those tools put their own short link in the pattern. The short link lives on their website, and they can turn it off when a trial ends. The square still scans. It just no longer has anywhere to go.
A static code stores the destination address. A dynamic code stores a short link that redirects to the destination. The redirect can be edited, measured, or switched off. A static code cannot be edited later, and it also cannot be switched off by the tool that made it.
A fixed code cannot be changed, because the address is part of the pattern. An editable code can. The pattern stores a short link on this site, and you change the address that short link opens. The printed squares stay the same.
A static QR code stores the destination. A dynamic QR code stores a redirect. The redirect is why a free code can die after a few days.
A QR code does not have an expiry date. It stops working only if the address inside it stops working, or if it stored someone else's redirect.
Use the full https address, leave a quiet margin, and choose Medium damage tolerance for a normal web page.
Print from the SVG when you can. Use black on white, keep the quiet zone, and scan a proof before the full run.