Add a channel twice, unsubscribe does not work

[Zykino]

Checklist

• I am using the latest version - 0.20.5
• I checked, but didn't find any duplicates (open OR closed) of this issue in the repo. I found some issues and a workaround (see at the end) but a bug persist so I still opened this issue
• I have read the contribution guidelines given at https://github.com/TeamNewPipe/NewPipe/blob/HEAD/.github/CONTRIBUTING.md.
• This issue contains only one bug. I will open one issue for every bug report I want to file.

Steps to reproduce the bug

1. Subscribe to a channel
2. Wait (long time like multiples weeks) I guess here there is a rename/URL change Youtube side
3. In the subscription page select a channel (did not happened to all of them, I found that Linus Tech Tips, Fermilab, Smarter Everyday among other have the issue on my phone)
4. Click on subscribe twice (sub - unsub)
5. Click on subscribe (once)

Actual behaviour

After 3, see in the channel page that I am not subscribed
After 4, on the subscription page see that nothing changed we are still subscribed to the channel
After 5, on the subscription page see that the channel is now present twice. And if we visit one or the other it is shown that we are subscribed. (But unsubscribing to one still keep one subscription in the list).

Expected behavior

After 3, the channel is written as subscribed and clicking on it once should unsubscribe me.

Device info

• Android version/Custom ROM version: OxygenOS 9.0.6 (Android 9 by the manufacturer)
• Device model: OnePlus 3

Workaround found on older/closed issues: long press to have an option to unsubscribe.
I still wanted to register the issue since compared to the older issue theses channels are not deleted. Also, the issue may be handled more smoothly by the app. (Changing the saved url when a redirect is detected ?)

[TT-392]

I was having this same issue for years, mainly noticed that I am effectively unable to unsubscribe from a bunch of channels I subscribed to a long time ago. Only just now found this issue and am happy to see the workaround.

I did some digging in the database file, and it seems that it is common to every subscribed channel had an url field that looked like:
https://youtube.com/user/username
Instead of:
https://youtube.com/channel/bunch of characters

Ig youtube switched to this new url format at some point and all channels you subscribed to before that happened now have this issue. I am honestly surprised it took me this long to find an issue mentioning the same thing, I feel like it would be a fairly common issue.