Do I have to use a VPN

[cg0]

All debrid services (RD, PM, AD) use encrypted servers, that means you won't get an email from your ISP telling you you streamed/downloaded something illegally.
If DMCA decides to get a court order (hasn't happened yet) to Real Debrid, they might find traces of your activity in their logs.
Premiumize is the only one DMCA can't touch due to their special encryption, described in full here:
https://tarnkappe.info/english/premiumize-me-our-lines-are-glowing-interview-with-the-ceo-41727.html

Reasons to use a VPN:
You need to access geo-locked content.
Your ISP throttles RD servers and you can't change to another ISP.
You don't trust your IPTV, in the past some IPTV devs gave their clients' IPs to DMCA.
You're using a torrent addon like Elementum (eg Diggz Xenon Burst Free build uses that addon) that uses live torrents when RD is not used.
You're downloading content from torrent sites using a torrent client.

What VPN should I use?
Read these and choose wisely.
https://restoreprivacy.com/5-eyes-9-eyes-14-eyes/
https://torrentfreak.com/best-vpn-anonymous-no-logging/