Gunnerzaurus
Hello,
You and every other person in the text conversation must have apple imessage or RCS for you to use RCS. If one person only has SMS, you all use SMS.
You could check these:
settings > system > reset > reset mobile
Make sure google messages is updated.
On the play store install page for the google messages app:
3 dots top right > automatic updates > enabled
Where you see "rcs connected" you can disable "automatically resend as text (SMS/MMS)"
For a specific conversation, 3 dots top right > details > only send SMS &mms messages disable this.
There could be an issue with:
A vpn, dns app, ad blocker, content blocker, or custom dns server.
Temporarily disable?