Will I lose podcast followers on Spotify if I switch hosting companies?
As long as you establish a 301 redirect from your previous RSS feed to your new one, your existing Spotify listeners will continue to get new episodes.
To redirect your old RSS feed after you've imported your podcast to its new home, revisit your former host and locate the section for feed redirection. Then, input your updated RSS feed URL from your current host.
If you don't have access to your old RSS feed with the previous host, just log in to Spotify's Podcast Dashboard and paste in your new RSS feed URL.