I ruptured my VMO thanks to a bad overuse injury a couple seasons back. It hit without any warning, but in hindsight the warning signs were there.
If the pain is very localised in the VMO, close to tendons, persisting and sharp (ie unlike the good kind of burn we get when riding at intensity) I would be very careful not to pedal too much or too hard for a while.
Bike fit may contribute to the problem, even cause it, and this surely varies case by case. But along with potential fit issues I would check if one has muscular / functional imbalances. IMHO the knee joint is a relatively simple hinge, and the soft tissues related to it are often victims of the bad company they keep, ie not very functional and/or weak hips and in some cases ankles, which are much more complex joints. Surely very badly positioned cleats and/or saddle may generate problems. However, per research (see for instance Rodrigo Bini’s or Phil Burt’s works about bike fit) the acceptable ‘fit window’ is often quite large for many if not most individuals, and we thus can absorb many kinds of suboptimal fits. My experience is the same.
So at a minimum, I would try to assess if there are weak / inhibited glutes (hip extension, abduction), weak and/or badly coordinated core, and tight / weak hip flexors (rectus femoris, tensor fascia latae, psoas) involved. There may be a ton of other issues, but I mention these just to paint a picture. Such an assesment is ideally done with a physiotherapist who is experienced with working with athletes and cyclists. If the problem lies in this area, the PT can hopefully teach one master movements that are effective for fixing the functional problems.
In my case the root cause were muscular imbalances typical to a roadie and a desk worker (quad dominance, tight hips, weak core, and especially underused glutes as well as badly controlled scapulae, and whatnot). This was exacerbated by several movement compensations developed to avoid the pain in the VMO, which both made the problem worse in an immediate sense (ie hurt, because wrong muscles were trying to stabilise the hip & knee in everything I did) and also prevented me to re-establish proper movement patterns.
So for me grasping and fixing the imbalances have been the key to recovery. Chasing pain in the VMO directly or attributing it mainly to bike fit were not very helpful. The recovery has been very frustrating and slow, but I am a better and more balanced rider these days.
Best of luck!