The latest commit is interesting (f9cf4c05edd14, "Fix sabotaged Landlock sandbox check").
It looks like one of Jia Tan's commits (328c52da8a2) added a stray "." character to a piece of C code that was part of a check for sandboxing support, which I guess would cause the code to fail to compile, causing the check to fail, causing the sandboxing to be disabled.
If your project becomes complex enough eventually you need tests for the configure step. Even without malicious actors its easy to miss that a compiler or system change broke some check.
It looks like one of Jia Tan's commits (328c52da8a2) added a stray "." character to a piece of C code that was part of a check for sandboxing support, which I guess would cause the code to fail to compile, causing the check to fail, causing the sandboxing to be disabled.