The dot notation feature (NODE-3589) introduced a limitation that prevents users from defining recursive (self referential) types on their schemas. We don't know how many users will be affected, but it would be worth investigating ways to mitigate the breakage.

Refer to the comment in the following community post: https://www.mongodb.com/community/forums/t/mongodb-node-js-driver-4-3-0-released/140479/2