I know they are used in google's BigTable. All data there is stored in seperate SSTables and you can specify that a locality group should have bloom filters generated for its SSTables. Apparently cassandra has them too.

Both are the same general application though and you already mentioned databases.

I did think about using them at some point for authentication purposes in a webservice. The idea being to check for double uses of a refresh token. This way the user database would need to store only a small amount of extra storage to check for the reuse of a refresh token and if you set the parameters accordingly, the false positives are kind of a benefit in that users cannot infinitely refresh and they actually have to reauthenticate sometimes.

Edit to add: I also read a paper recently that uses a datastructure called a collage that is closely related to bloom filters to perform in-network calculations in a sensor network. If I understand correctly, the basic idea there is that every node in the network adds a bit to the datastructure while it is in transit, so data from the entire network is aggregated. The result can then be fed to a classifier ML model. (Source: Oostvogels, J., Michiels, S., & Hughes, D. (2022). One-Take: Gathering Distributed Sensor Data Through Dominant Symbols for Fast Classification. )