Long-lived connections from Bitcoin clients that only listen to transaction INVs but never request transactions caused problem. While this problem is fixed in the most recent releases (23.2, 24.1, and 25.0), some network participants (e.g. mining pools running custom patches) might not be able to upgrade immediately. A solution is to ban the entities making these long-lived connections. Some of the entities are likely "spy-nodes" while others are "network monitoring tools" by researchers.
There's a special and temporary version of this banlist that bans these entities for 90 days. It can be found in this branch.