Smiles! this got me smiling like it makes me look stubborn tho.
Some other customizations I have even forgotten them but they all in my style (theme)
Yes, I can try to find the codes. But also some extensions that I have installed may not be compatible with the latest phpBB version.
See the phpBB 3.3 requirements.
Rocket science provides 2 solutions:
Than it is time to start with the recommendations we give you last year
What are these non-compatible PHP 8.0 extensions?