Trezor seed phrase confusion

My Trezors seed phrase is 20 words and upon on researching it its shown to be a SLIP39 or Shamir Backup. My question is the website shows that both of them require multiple shares in order to fully back it up even though I only have one. Wrote it down, had a practice backup and everything but I didn’t notice it until now. Any clues on whats happening. Thank you very much for any help

The Shamir backup gives you the option of splitting your backup into multiple shares – either right at start, or at any later time, if you choose to do so.

By default, it’s just one share, so that you only have one thing to keep track of.

(But when you feel comfortable, do look into the sharding functionality. Making e.g. a 2-of-3 backup and handing it to three distinct friends or family members is a great way to protect yourself from theft and from the risk of loss at the same time.)