PPM in veg is lower than online readings

Suggestions and recommendations are a good place to start.. Always read and react to the plant from there.. forget "what should be." You VPD can impact rate of plant drinking and that can impact the 'optimal' overall concentration (assumes well-balanced ratios too). my vpd tends to be a bit higher, and regularly feed at 600-650ppm because of that when gassing the lights in 12/12 schedule (heat). In vege i need it's closer to 700ppm but relative to rate of drinking is roughly the same mass of fertilizers given per day, rate of provision = rate of growth (relative to local variables) avoids toxicities and deficiencies. The close you are to reaching that proper balance, the longer it takes to see any issues over time. Keep track of how you fed over time. sometimes takes a month or two to see an issue from a formula.

It's not that low. It kinda depends on where you're starting from. A lot of well water runs 200-400 out the tap but if you're using filtered water it might be less than 50. How do your plants look? You're better off underfeeding a few weeks and catching up later than to overfeeding and potentially stunt/burn/lockout your plants.