Earlier this month, reports noted that Rey Mysterio's WWE deal had expired and he was working for the wrestling behemoth without a contract. Mysterio reportedly asked for a pay rise while negotiating over the new contract, but Vince McMahon was unwilling to accept his demands because of the releases back on April 15 and the company's financial situation during the ongoing coronavirus pandemic.
Both sides have continued negotiations and The Master Of The 619 was prominently featured on WWE TV until The Horror Show at Extreme Rules in his rivalry with Seth Rollins. Mike Johnson at PWInsider recently noted Mysterio travelled to Stamford, Connecticut for talks last week, but a new deal had yet to be agreed.
This could change in the near future as Dave Meltzer reported in the Wrestling Observer Newsletter that the two parties aren't too far apart on a new deal and Vince McMahon and the former World Heavyweight Champion will be meeting at Titan Towers again soon to try and finalise the new contract.