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


There is an existing OSM based map https://veggiekarte.de/ that also has filtering options. The biggest issue is that OSM doesn’t have much detail on POIs and they’re often out of date. Even in Western Europe where most other stuff is up to date. Mostly because POIs require on the ground surveys which only a handful of contributors can do in more than one region.
So, please consider contributing to OSM using simple apps like StreetComplete or EveryDoor if you have some spare time.