follow all your steps but after last reboot its 10.3.8.GM21AA again and asks to updateOk guys, answer to your questions is so simple but you all are getting confused may be.
First of you need to know that Stable TWRP is not available for OOS 11 Stable and Beta. To use TWRP and OOS 11/Beta together your device must be decrypted.
NOTE: If you are already in bootloop or something after flashing oos 11 with twrp then check my this post. There you have only two options to get back and then follow below steps if you need
Now here is a perfect drill
It will make 0% chances of any bootloop or anything.
These steps will let your device boot up 100% with exact 0% chances of any bootloop
First download Latest "Disable Dm verity and force encrypt zip" from attachment.
Now things you need:
A PC/Laptop with cable or USB OTG drive with required files in it.
1. Latest Official TWRP Installer zip
2. Latest Magisk zip
3. Latest Disable Dm verity and force encrypt zip
4. And obviously OOS 11 rom zip file
Now follow steps below
Main Steps you need:
1. Backup data (If you have data and need that)
2. Boot in TWRP and factory reset.
3. Format Data and type yes to format it.
4. Install oos 11
5. Install TWRP installer zip
6. Install Magisk zip
7. Install Disable Dm verity and force encrypt zip
8. Reboot Recovery
9. Install Magisk again
10. Install Disable Dm verity and force encrypt zip again
11. Reboot and you are good.
There is 0% chance of any bootloop if you follow this.