The drive is always encrypted. Data on the drive is decrypted on the fly as you read it. And anything you write to the drive is encrypted on the fly as it is written.
Suspend should not affect that.
If you suspend to memory (sometimes called sleeping), the encryption key should still be retained by memory, so it should resume without an issue.
If you suspend to disk, then the machine state is saved to swap. On restart, you might need to give the encryption key before it can resume. However, if you are using UEFI with secure-boot, then system lockdown might be in effect. I’m not sure what happens in that case.