I’ve upgraded @icp-sdk in probably 10 projects or so, so I’m quite confident there is no relationship between the @dfinity and @icp-sdk libraries and the other dependencies you mentioned in the thread.
Just my two cents: I would recommend upgrading one or the other, but not both at the same time. Either migrate to v4, or update your outdated libraries but avoid mixing both approaches.
But I’m with you, upgrading outdated JS libraries is always tricky! 