Ping on my server appears to skyrocket near nether portals, dynamically based on distance.

this server is running paper#76 with no plugins altering portals in any way on the Shockbyte 8gb plan hosted in Virginia (I am a few states away).

also tested this on a self hosted fabric-cardboard server AND a self hosted vanilla server with a vanilla client with the same result.

also tested with end portal with seemingly no issues, just the nether portal.