It’s not a perfect replacement, but searching OpenStreetMap via https://overpass-turbo.eu/ with a query like
[out:json][timeout:25];
(
nwr["diet:vegan"~"yes|only"]({{bbox}});
nwr["cuisine"~"vegan"]({{bbox}});
);
out geom;
can be useful and is often more up-to-date with respect to restaurants that actually still exist.
An example: https://overpass-turbo.eu/s/2shI
My post may well be tainted by my growing frustration with HappyCow growing increasingly out of date in my region. I frequently find restaurants listed that have long since closed and new restaurants not listed at all. But criticism in my workaround and its deficiencies has been wholeheartedly acknowledged and appreciated.
Though HappyCow is closed-source and proprietary, it’s like OSM in that it relies on user reports. Have you submitted new restaurants and reported closed ones?