So, the twilight forest portal is a ring of grass or dirt blocks surrounding a 2x2 portal. With sloping blocks, the grass blocks see the portal blocks as 'empty', sloping downwards.
But when you go through a Twilight Forest portal, it typically places you on the edge of the portal, on the sloped-downwards edge of the grass blocks, causing you to immediately fall back within the bounding box of the portal blocks, triggering another dimension transition. It is easy to get stuck this way indefinitely, as the server will frequently already be in the process of beginning another dimension transfer before the client has enough information to render the current position, leaving the player without much recourse except to hope they land on 'solid enough' ground.
One solution would be a config option for blocks that can be used to force adjacent sloping blocks to consider them 'solid', and not slope down towards.
So, the twilight forest portal is a ring of grass or dirt blocks surrounding a 2x2 portal. With sloping blocks, the grass blocks see the portal blocks as 'empty', sloping downwards.
But when you go through a Twilight Forest portal, it typically places you on the edge of the portal, on the sloped-downwards edge of the grass blocks, causing you to immediately fall back within the bounding box of the portal blocks, triggering another dimension transition. It is easy to get stuck this way indefinitely, as the server will frequently already be in the process of beginning another dimension transfer before the client has enough information to render the current position, leaving the player without much recourse except to hope they land on 'solid enough' ground.
One solution would be a config option for blocks that can be used to force adjacent sloping blocks to consider them 'solid', and not slope down towards.