Meta rejected my template and the reason is vague

Template rejections almost always come down to one of four causes. Unhelpfully, Meta rarely tells you which one.

1. The category does not match the content

This is the most common cause by a wide margin. A template filed as utility whose wording reads like marketing, anything with "discount", "offer", or "special deal", gets rejected or forcibly moved into the marketing category, which costs more to send. The working rule: if the message benefits the customer (a reminder, a confirmation, a status update), it is utility. If it benefits you (an invitation to buy), it is marketing.

2. Variables with no sample values

A template with changing parts such as {{1}} must be submitted with example values. The WACO template form requires them before it will let you submit, and the number of samples has to match the number of variables exactly.

3. It reads like spam

ALL CAPITALS, stacked exclamation marks!!!, or overreaching promises ("guaranteed", "100% certain"). Write it the way you would write to one real person, because that is exactly how it will be read.

4. It is too generic

A template that is nothing but {{1}} with no fixed wording ("Hi {{1}}, {{2}}") gets rejected, because it could be used to send anything at all. The fixed part has to make the purpose of the message clear.

An example that passes

Hi {{1}}, this is a reminder of your appointment at Bright
Dental on {{2}} at {{3}}. Reply to this message if you need to
reschedule. Thank you.

The purpose is obvious, the fixed wording carries real meaning, and nothing is being sold. Filed as utility, this is almost certain to be approved.