The term "lab leak" is ambiguous (deliberately I guess) as to whether the virus was modified in the lab before it leaked, or if the lab leaked an unmodified virus.
But the preponderance of evidence is that the leaked virus was modified before it was leaked. The critical spike protein in SARS_CoV2 is coded uses a sequence of amino acids that has never been seen before in any other coronavirus. I forget the names, but there are certain common amino acids that can be coded using several different functionally-identical DNA (RNA) sequences, and the SARS-CoV2 one looks like the sequences used in labs and humans, and never seen before in natural viruses. One nobel laureate in biology described this as a "smoking gun" that this was a lab leak when they first heard about it.
But the preponderance of evidence is that the leaked virus was modified before it was leaked. The critical spike protein in SARS_CoV2 is coded uses a sequence of amino acids that has never been seen before in any other coronavirus. I forget the names, but there are certain common amino acids that can be coded using several different functionally-identical DNA (RNA) sequences, and the SARS-CoV2 one looks like the sequences used in labs and humans, and never seen before in natural viruses. One nobel laureate in biology described this as a "smoking gun" that this was a lab leak when they first heard about it.