The database connection pool used to be 18. The old limit was set to allow bors-ng to run on a Hobby Postgres database on Heroku (plus two connections for you to use for administration). This is still the default if you use the Heroku Button.
However, we exceeded the data storage limit of a Hobby database awhile back, and app.bors.tech is now running on a standard-0 instance, which has a connection limit of 120.
The bors-ng-internal limit is set to 50, now, because I’m trying to limit the amount of RAM consumed by the web dyno itself. If we start reaching this limit, I’ll have to look into moving off a hobby web package onto a standard web package, which is going to be annoying.