@ricmac I already had contacted hostinger and the last message I received was "we are working on it". sadly this is an issue that I can't solve on plugin level and WebFinger is something that is required at least from Mastodon.
Buuut... if you want to use only one account, maybe this will help with your issue: https://wordpress.org/support/topic/pixelfed-%e2%9c%85-mastodon-%e2%9d%8c/#post-16884865 ?!?