New characters have same glyph as old characters. It's the nightmare. For example, I can't find old one by searching new one. It's hard to know the reason for normal people. Should all software support searching by both characters? I don't expect all western developer take care. Equality comparison also fails without special support.

That is a bad exuse since it would preclude adding any new characters for existing languages. Would you have made the same objection for U+1E9E "ẞ", which was added in 2008?

Also, equality comparison already requires special support, e.g. normalization before comparison.

Sure, there would be an period where software support is incomplete but that is a bad reason to keep things broken forever.

It doesn't seem unfeasible to make a search that would support both.

It's possible to implement, but it makes confusion than benefit until all existing software support it.