If you visit the URL, it’s an RSS feed. How critical it is to block or not depends on your threat model. You should share your threat model in order to have meaningful discussion around what it is you are concerned with.
Unless someone has poisoned your DNS to link to a different RSS feed, this is all extremely normal. To check for updates, an application may check some server somewhere to see if updates are available. This doesn’t just apply to applications - even a Linux package manager has to make a network request to check for updates. Very normal.
The only thing that is important is that checking for updates is separate from applying them - they should never be glued together so you can control when or if you want to update.
Regardless, if this behavior isn’t wanted, check if the application allows you to disable checking for updates. If not, and this is a concern, open a bug report on GitHub, and someone may add a setting to disable checking for updates.
As for someone snooping on your updates, it uses HTTPS so the request and response is encrypted. As for someone knowing you made a get request to a FreeTube update server if they are intentionally spying on your DNS queries, use a VPN and ensure you aren’t leaking DNS.
As for security risk, it’s pretty much FUD unless someone is actively targeting you to trick you into installing a malicious FreeTube update as worst case scenario. If this is a discussion on general opinions of this, I’d say it’s bike shedding and there are more important things to focus on for privacy. If this is about a specific concern of yours, I believe the above suggestions mitigate most of the problems.