Nodes with low upstream capacity might be poorer connected or under higher load or have other bottlenecks. Running 50 nodes on one VPS is not the same as 1 node on a barebone.

How do you figure? There aren't significant differences vs. Core in the relevant part of the code.

Possibly, if a lot of them are sybils. nostr:nevent1qqsydp3eh0ksd7rrmfgp574vh3w2y8d5yppl39mkaws9crvgeqvcgfcprpmhxue69uhkummnw3ezumr0wpczuum0vd5kzmp0qgs0w2xeumnsfq6cuuynpaw2vjcfwacdnzwvmp59flnp3mdfez3czpsrqsqqqqqpx77get