Can confirm this bug still affects 1.17.40 on Windows 10. It seems that anti-aliasing is working properly on black outlines created by looking at a block, the player model itself, and outlines of blocks not highlighted by the player. It is still broken on block textures, foliage, torches, signs and I'm assuming many other things. I figured I'd add some pictures.
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It wasn't in the changelog for 1.17.41, but this issue wasn't fixed. I can confirm the behavior AegisFalcon explained as well.