Purely for the sake of conversation, a ways back -- long enough I don't remember the source -- I read a series of articles written with virologist, epidemiologist, and military contribution, discussing traits that would be considered ideal in diseases for use in biological warfare, and those traits that would negate their utility as biological weapons. What stuck with me about these articles, is how counter-intuitive popular assumption is when faced with the realities of various diseases and whether they'd be successful vectors for bio-warfare. Which is pretty much the only reason most states would be interested in genetically-modified disease strains, other than as a vector for vaccination against more serious diseases (see, the intentional spread of cowpox to vaccinate against smallpox in the days before contemporary vaccination).
What struck me as interesting about these articles, was the traits the public typically associates with diseases that would make good bio-weapons (thanks to the media) are traits that would actually make them non-viable as such. The multitude of VHF's for example being discountable almost immediately, because they're lethal but not terribly contagious, and their high-profile symptoms make them unlikely to spread in a population once the disease is identified and quarantining can start. Even anthrax was largely discounted by these articles as an artifact of early- to mid-20th Century medicine, because while spores may be resilient and easily spread, it's not communicable and vulnerable to contemporary antibiotics.
The thing with COVID that makes its epidemiology suspect, is that it does -- by accident or not -- hit all the major markers of a disease ideal for biological warfare. Highly contagious, short latent period but a longer period in which a patient is asymptomatic but infectious, not terribly lethal but crippling to a population and infrastructure. Key to remember with this, is the goalpost of biological warfare isn't necessarily to kill large swaths of a target population but rather to incapacitate them and thereby degrade economic or warfighting power.
More than anything else, I believe that's the muscle behind the perpetuation of the "lab-made" origin theory. And I say that as someone who does buy somewhat into the theory -- enough to believe it worth serious investigation, at least.