I am planning on changing my blog name and redirecting my blogger blog to a custom domain. Why would that affect my Facebook followers?A Blogger URL change won't affect your FaceBook Followers directly. Your existing Followers can continue to Follow your blog, under the BlogSpot URL - and under the custom domain URL - as it is Liked, and shared, in FaceBook.
The Likes count affects the possibility of a share, of a post in your blog, to attract new Followers.
URL changes, as permitted and provided by Blogger and / or FaceBook, are easy enough to make.
If you change the URL of the blog, when it's later shared in FaceBook, you will have a different blog. If you redirect your Blogger blog to a properly setup custom domain, you will have a blog that is shared under a different URL - and you'll have a new Likes counter.
A Like will be counted against the URL of the post that is Liked.
If someone Likes your blog in FaceBook, the Like will be counted against the URL used to address the blog, in the FaceBook post being shared.
You can either count your Likes under the current BlogSpot URL - or the new URL. Just choose the URL that's used, when it's shared.
If you publicise the blog, in FaceBook, using the current BlogSpot URL, the Like will be applied against that URL. This will not contribute to popularity of the custom domain URL - and the new blog identity. The custom domain will get no Likes - and the blog will continue to be seen, in Facebook, under the BlogSpot URL.
If you publicise the blog, in FaceBook, using the custom domain URL, the Like will be applied against the custom domain URL. The blog will not benefit from popularity of the BlogSpot URL - and the current blog identity. The BlogSpot URL will get no Likes - and the blog will be seen, in Facebook, under the custom domain URL.
You are allowed to change the blog URL, by both Blogger and FaceBook.
You are allowed to change the URL of the blog, in Blogger. You can change the BlogSpot URL, to a different BlogSpot name. You can change the domain URL, to a custom domain. You can change both the BlogSpot and domain URLs, if you wish.
Either way you change the URL, you will end up with a different URL, when shared in FaceBook. And with your posts shared using a different URL, you will have Likes counted using a different counter. This isn't a question of what FaceBook lets you do - it's a question of how they count the Likes, that apply to your blog.
You will need to move forward, using your new custom domain URL, and starting with 0 Likes - or stay where you are, using the current BlogSpot URL, and continuing with the current Likes counter. FaceBook will let you do either. They just won't be able to help you do both, at the same time.
This is really just one more detail, in re indexing a blog, after a URL change.
If you change the URL of a #Blogger blog, #FaceBook popularity will be affected. You (or any reader) can share the blog using either the current or new URL - and any Likes received for a share will apply to the URL used.
The blog will appear under two (or more) different URLs - a known effect of republishing.