@Zahmi Zuhair Thank you for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
Yes, you need to redeploy your application and reconfigure the custom domain to a app service on Linux app service plan since starting from php 8.0 is supported only on Linux app service plans and also, we don't have any mechanism to move the php application which are targeting from windows-based app service plan to Linux based app service plan.
Feel free to reach back to me if you have any further questions on this.