Looks like Ellis is out of contract in Aug 2021.
On 21 May 2018 Ellis signed a two-year deal for newly promoted Tranmere after electing not to resign with Carlisle.[19] Ellis ruptured his ACL in April 2019,[20] making his return ten months later in a Cheshire Cup fixture against Crewe Alexandra.[21] He signed a further one-year deal ahead of the 2020-21 season. [22] On 8 March 2021, Ellis joined National League side Notts County on loan for the remainder of the 2020-21 season.[23]
https://www.tranmererovers.co.uk/new...one-year-deal/