Earlier quoted context omitted.
The license doesn't look very open. https://github.com/getkirby/kirby/blob/main/LICENSE.md
There is at least 1 LGPL dependency in there which renders the license void. If you include LGPL, your software is LGPL.
That would be the regular GPL. The "Lesser" GPL allows you to use it as long as you release any changes you make to the LGPL'd code (and keeping the LGPL license) and allow users to replace the LGPL'd code, which typically means using it as a shared library.