facing problem

Hello, I just upgraded my php from 7.4. to 8.1. Most of my website works fine, however, when I switch languages I get the error "Unsupported operand types: string + int"

I use the latest Joomla 4 version and the Helix 3 template.

I found a similar post here : 

 It seems that the template needs an upgrade, right?

When can this be expected? - php 7.4 is not supported anymore...

Thank you!