With `level-type=amplified` or `level-type=AMPLIFIED`, the vanilla 1.18 Pre-release 1 server jar generates a normal world, instead of an amplified one. This is similar to MC-187522, but it happens in the latest version ;p

The server seems to properly interact with worlds generated in single-player mode, further generating an amplified one instead of a normal one, although I've noticed a badly generated tree around a chunk boundary at -458 / 157 / 351 (see screenshot). My client has a render distance of 12 chunks, the seed is attached in the server.properties file.