In a recent update recent update, gate size restrictions were put in place that did not allow for aircraft of a certain size to spawn in a gate that’s to small for their aircraft type.
In it’s first iteration however an “intentional“ sacrifice was made, as noted by Infinite Flight ATC Community Manager, Tyler Shelton. “Currently we take whatever is the appropriate size and allow one category above it. This was to avoid such a drastic change overnight that may be overly restrictive in unexpected cases or scenarios where a gate could’ve been incorrectly categorized. We’ll continue to monitor and improve on this in future updates!”
Always check the size restrictions at the airport yourself before starting. There’s a ton of things you can and need to check.