Https://leantime.io (Disclaimer: I am the founder)
Leantime founder here: Sorry you were running into issues. Did you ever get to update your PHP version to 8 and Leantime running (https://github.com/Leantime/leantime/issues/2006)? We didn't hear back from you after you submitted the initial issue on Github. Would love to know what was slow or the CSS issues you were encountering.
Leantime founder here. I am sorry you were running into issues with Leantime. Based on your GitHub issue https://github.com/Leantime/leantime/issues/2006 and discord messages it appears that you are attempting to run Leantime on a server with PHP7.
We dropped support for 7 a while ago. (Keep in mind that your CLI can run a different PHP version than the actual server).
The line in the code called out is a private variable definition with 3 different potential types. This was introduced in PHP8.
We‘re always happy to help get your Installation running but the min system requirements need to be met.