Information about DNS and network

I have a domain with register.com that has some outdated glue records that I need to update. I contacted register.com and they said they don’t support glue records and if I want to change it I’ll have to rehost my domain with another registrar.

So if I transfer my domain to a new registrar the glue records won’t transfer over? or?

confused. thanks

Tried googling and searching this subreddit too and found nothing

Also Cloudflare and Quad9 free DNS services seem pro privacy consumer etc and even hire people to check they don’t store logs

Surely all these costs them money right?

Im from the UK and want to try these DNS services away from the default one i have with Sky broadband but this makes no sense to me why they are free especially Cloudflare and Quad9

Just changed my routers settings to 1.1.1.1 and 1.0.0.1.

Is anyone else using this?