Hello, that looks like Sequoia pitch moth caused pitching.  Resin accumulates in those blobs, often at branch junctions.  The insect larva (caterpillar) is there under the blob for two years, and after it pupates exits the blob and leaves a distinct hole.  The resin can last for years even though the insect is gone.  However, a new generation may infest the same area, and you can get lots of these, like in your picture.

Here are some links:
https://www.fs.usda.gov/foresthealth/docs/fidls/FIDL-185-SequoiaPitchMoth.pdf

https://extension.oregonstate.edu/sites/default/files/documents/em9008.pdf  (page 9)

We don't think this will kill the tree, but it is ugly.  These links above have lots of info about what to do.  In general, not to worry too much.  You can scrap these off the tree, and if the resin blob is still soft, there may be a caterpillar under there.