The icicles are not setting of the maximum building height heads up in the chat while sulfur spikes do. Weird thing is it does stop you from placing higher than 320 blocks. As shown in this media.
Steps to remake:
Make a new world with experimental fourth drop toggle.
get a normal Minecraft block and the icicle and the sulfur spike
build to build height
Take note of what happens
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Here is all of the media that shows this.