EDIT: Thank you to u/bluesix_v2 and a few others for teaching me about Must Use Plugins - I had no idea that you could just hide secret plugins in the backend of WordPress that wouldn't show up in the dashboard - after deleting some Hostinger mu-plugins, not only is the problem fixed but my website has suddenly started running ten times faster. THANK YOU!

Exactly as the title says, I can't update WordPress right now because, even after going through all the correct channels to transfer my website from Hostinger to my new host IONOS (yes I know IONOS isn't great but it's cheap and I'm broke), every time I attempt to update WordPress, I get the following error:

"Download failed.: cURL error 28: Failed to connect to wpdownloads.hostinger.io port 443 after 10006 ms: Timeout was reached"

It's clearly still trying to download things through Hostinger, despite the website having been fully transferred away from Hostinger, domain, database and filesystem.

I've cleared all references to Hostinger from the database, removed all Hostinger-related plugins, there shouldn't be anything left of Hostinger in this website, but obviously I've missed something. Does anyone have any idea where this final remnant of Hostinger's code could be hiding in my website?

This is preventing me from keeping my website up-to-date so it's a very pressing issue for me. I'd appreciate any and all help!