Is Ubuntu 20.10 obsolete now?

I got a new computer and because I wanted really strong audio recording support, and because I previously had Kubuntu, I installed Ubuntu Studio 20.10. https://wiki.ubuntu.com/UbuntuStudio

It says that 20.10 is only supported until July 2021! What should I do? Do I need to do a system re-install with a different distro?

There are two cadences for Ubuntu releases.

Standard releases are released every 6 months and are supported for 9 months after release.

LTS releases are released every 2 years and come with 5 years of support. (Note that official flavors of Ubuntu LTS releases are only supported for 3 years)

Ubuntu version numbers are in YY.MM format, so Ubuntu 20.10 was released in October, 2020.

Ubuntu 20.10 is a Standard release and will become EOL this month.

You should upgrade your system to Ubuntu 21.04 before your current release goes EOL.

If you do not want to upgrade your system every 6-9 months, you should use a LTS release.

Here is a list of releases and their support status.

For more information, visit "The Ubuntu lifecycle and release cadence".

Refer to @Nmath's answer for details on your release choices.

For how to upgrade I'd always suggest reading the release notes for the intended path, ie.

Ubuntu Studio 21.04 (next release after 20.10).

It has an "Upgrading" Section

Upgrading

Due to the change in desktop environment this release, direct upgrades from release prior to 20.10 are not supported.

In the coming weeks, you should see a prompt to upgrade from 20.10 during your regular updates. If you wish to update at that time, click “Install Upgrade”.

The caveat doesn't apply to you (you're on 20.10, and not a release earlier than that) so you can upgrade when it's offered.

After reading the release notes that apply to you, I'd normally recommend reading the main Ubuntu 21.04 release notes which likewise have a "Release Upgrades" section on the topic. It warns that a shim bug was blocking upgrades when 21.04 was released (it got fixed, then another bug was blocking it, that too has been fixed).

Upgrade instructions can be found at https://help.ubuntu.coam/community/HirsuteUpgrades

Note: As Ubuntu Studio uses the KDE desktop, I'd also read the Kubuntu Desktops link provided in the HirsuteUpgrades link, ie. https://help.ubuntu.com/community/HirsuteUpgrades/Kubuntu (where you'll find the command though I copied it from Lubuntu documentation as we use Qt too)

The command to upgrade is

do-release-upgrade -m desktop -f DistUpgradeViewKDE

if you'd like to do it via terminal, but given the release notes for Ubuntu Studio 21.04 recommend accepting it when offered; I'd follow that advice.

Note: the command is needed should you be offered the upgrade; but opt No & don't ask me again, thus need to start the release-upgrade yourself.