It can restrict the intended spaces around the load or obstruct air movement. A tray that physically enters the cavity is not necessarily an approved fit.
What the observation means
The manufacturer's accessories are sized around shelf supports, walls and heat paths. An unusually wide aftermarket tray may touch surfaces, sit at the wrong height or cover a large portion of the cavity. Those changes matter even if the door can still close. They can also make hot handling difficult when the tray is loaded.
A useful next step
Compare its dimensions and support arrangement with the appliance's instructions. Use only compatible cookware that can sit securely on the correct shelf. Mention the oversized tray if a cooking change began after introducing it. Do not bend shelf supports or remove internal panels to make a larger item fit.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.