datasets with variable maxzoom

[prusswan]

Related to syncpoint/openvtpk#22, apparently vtpk can contain a mixture of maxzoom (15 and 16). So for the affected areas, the client needs to be able to retain data from the previous zoom, and not blank out just because no data exists at maxzoom.

#48 seems to suggest Leaflet is not able to support such data, but MapLibre does, is this understanding correct?