Track goes from dry to wet.
Also that they keep two bikes with different tires to swap out as needed.
Ah! Thank you! That's why the commentators were concerned about damaged bikes then!
Edit to add I'm pretty sure I upvoted you but it's still only showing one, sorry not sure what is going on.
I was trying to find a good reference but all I could find was bloated SEO garbage.
I think the deal is that a flag-to-flag race is not red flagged when it starts to rain. Instead the riders can switch bikes, which is not normally allowed.
I agree that technically all races are flag to flag, but yes, when they say "flag to flag" they mean a wet race where the riders are allowed to change bikes when conditions change - instead of just stopping the race.
Flag to flag coverage? Means the whole race is covered by the media.