I deleted the Source and added it back with a different Source name using the php version and set it to 7000. It did start at 7000, but the last channel for it is 11440. There is another Source above 7000 that it went through, so hopefully no conflicts.
The only other thing I can think is that I added the FrndlyTV Docker source a few days ago, and that one uses 2 separate sources, only one of which has a guide url, in order to get all the channels. When I set that up, it had 4 times as many channels for itself which I just turned off in the settings.
Deleting and recreating guide data didn't solve it.