Sure, but it's probably best to try to avoid baking the belayers into the air in the first place instead of hoping and assuming they'll maintain best belaying practices while being abducted into the sky.
Being pulled up onto the air is not abnormal when belaying, and is a sign that they are giving a soft catch. Granted with a belayer who is much lighter than the climber this can end up being "too soft", risking a ground fall lower on the route. Something you'll also often see is unclipping the first quickdraw to give the belayer more space to "fly".
This is why belaying a lead climber shouldn't be considered a casual activity. The belayer literally has the climber's life in their hands. In addition to violet jerks, the belayer needs to keep their hands on the belay strand even if hit by falling rocks.
Also, use of belay gloves can help a lot and I think is more emphasized in Europe than the US.
Sure, but any safety paradigm that begins and ends with "(people) should/n't x" is a bad safety paradigm across anything enough people do enough of. It's probably easier to compensate for weight differences with a tether or weights than to convince people to spend long periods of time on high alert with low chance of incident.
Indeed. When I mentor new lead climbers/belayers, I point out that lead belaying should feel about as stressful as lead climbing. If it doesn’t, you’re not paying attention.
In my climbing group, we consider a weight difference of more than about 25kg to be too dangerous when leading. It’s definitely a safety issue for both climber and belayer.
At two meters tall and 93kg, by necessity I own an Ohm (by Edelrid), which buys an extra 20kg or so of margin.