Hello Wilber,
it's me again. :)
Toufig confirmed today that the development team is now working on PHP8 compatibility for the Helix3 templates.
https://www.joomshaper.com/forum/question/12450#qa-answer-83491
Developer team started work on PHP 8 compatiblity of Helix3 on this week.
Here you have two options.
You can use the patches from me or wait for the development team.
If the server update should take place before the update by the developer team, you can use the patches from me as a transitional solution.
With the update by the developers, these will be overwritten and replaced by those of Joomshaper.
For Helix 3 templates you can find some of the patches under the following post.
https://www.joomshaper.com/forum/question/17313#qa-answer-83050
Have a nice day.