What is a chain redirect, and why are they bad?

In a nutshell, a redirect chain occurs when there are multiple redirects between the initial requested URL and the final destination URL.

For example, URL-One redirects to URL-Two, which in turn redirects to URL-Three. This means that URL-Three takes longer to load, for both users and crawlers.

Why are chain redirects bad for SEO?

There are three reasons to avoid redirect chains.

1. Crawling challenges

1. Google typically follows up to five redirect hops during one crawl before it aborts the crawl session. This negatively impacts your crawl budget and may lead to indexing problems.
   

2. Lost link equity

1. Not all page authority or link equity gets passed through a redirect. This means that even one extra hop in the process can decrease the amount of page authority passed from the first to the last URL. For example, if you have three redirects in a chain, and you lose 5% of link equity with each redirect, the destination URL will receive only 85.7% of the link equity of the original URL. If there is even a single 302 redirect in the chain, zero link equity will get passed through.
   

3. Increased page load time:

1. All redirects must be processed before the final destination URL can begin to load. Since bounce rates begin to increase after only 2 seconds, saving every millisecond of page load time is essential.

Additional information:

https://developers.google.com/search/docs/advanced/crawling/301-redirects