You're messing with partitions which means there is the potential for data loss, be it hardware, human error, or a random cat. You should, if the data is important to you, have a backup.

Is it read only?

Through its ears?

Why?

Let me put the question back to you. How do think the uniquely identifiable information will help them improve Manjaro?

Do you think they’ve got a Russian satellite and will track down your HDD serial number from space?

No.

There’s lots of benefits to telemetry.

As I basically said, if you bothered to read my comment.

They’ve let TLS certs expire on multiple occasions.

And they told their community to set their clocks back. As a workaround, it will work but all your created and modified data will have the wrong timestamps.

enable telemetry by default ... MAC addresses, disk serial numbers

Another reason to not use Manjaro. Just use Endeavour instead.

Edit: I'm not against telemetry pre se. I have the KDE feedback enabled for example but that was opt in and sends no unique data.

I hesitate to say

I thought (s)he was a maine coon

I go where the cats are!

You can't fool me, they have another daemon for that

Update /etc/systemd/resolved.conf and add some DNS servers (in this example, 1.1.1.1 is CloudFlare, and 8.8.8.8 and 8.8.4.4 are Google but you can use your preferred DNS servers.)

[Resolve]
DNS=1.1.1.1 8.8.8.8
FallbackDNS=8.8.4.4

Restart system resolved:

service systemd-resolved restart

Run resolvectl status (or systemd-resolve --status in older versions of systemd) to see if the settings took.

If they don't take after a reboot, there's something else going on.

Pro: you have a custom kernel.

Con: the next morning, you can have a non-functioning computer with no idea of what you did.