5xx errors in the search console

Hi guys, hopefully, someone can help me. I have problems with 5xx errors in the search console. Now how i end up with 5xx errors with one stupid small mistake?

I was redesigning my website and while redesigning, I linked the theme preview in my footer by mistake. After 10 min of testing the site, I realized that I linked the theme preview in the footer. Great thing is that I had bad luck and google crawler was on my site in that 10 min and found that link.

Basically, instead of linking /about-us.com, i linked about-us.com/?customize_changeset_uuid=-&customize_autosaved=on

You can see site preview only when you are logged in but if you are not you will see this message: Non-existent changeset UUID. So google is not able to access it.

Now I have around 35 server errors 5xx. But to make things interesting and what I do not understand is if google is not able to see theme preview, how the f he could find 30 theme preview links if the link of that theme preview was about us page. Some crazy stuff.

There is no information on how to fix this. Changing permalinks and redirection does not work. Also how much impact this will have on SEO?