assuming a zap request could be shorter than 639 bytes it would also not work.

I don’t know the bolt11 details well enough.

Even if it’s their fault to not implement the bolt11 spec perfectly the state is that some big implementations have this problem.

It limits how zappers can be built. LN implementations have problems, not to talk about tools like lnbits, strike, etc.

those can not be used because of this limitation.