The authors of "Deadpool 3" planned a cameo by Patrick Start

The authors of the film “Deadpool 3” initially planned to implement a cameo in their project by Patrick Stewart, known for his role as Professor X in films about mutants.

However, over time, this idea was abandoned, as the pandemic made adjustments to the team’s work. Also, the plans of Marvel were affected by the strike of members of the Writers Guild, and Stewart himself was no longer young, so his health also had an impact on the schedule.

In short, our beloved Charles Xavier will ultimately not appear in Deadpool 3. At least, performed by his canonical actor.