How does the donation cooldown work?

I recently got a 'donation cooldown' notification, preventing me from donating cards further:

What triggers this? How does the donation cooldown work? Is there a specific time when the daily donation limit resets? When I got the donation cooldown notification, it didn't start from 24 hours, but from around 35 minutes.

The donation system now works this way:

Every 7 hours, the members of a clan can ask for cards (common and rare during the week, epic during Sunday). Depending on your arena level, the number of cards you can give/receive is modified. If you donated too many cards during this 7 hour period, you will then have the cool down, preventing you from asking/giving further cards.

The number of cards you can ask/give for each arena is the following:

Goblin Stadium

• Donating: 1 common card or 1 rare card.
• Asking: 10 common cards or 1 rare card.

Bone Pit

• Donating: 2 common cards or 1 rare card.
• Asking: 10 common cards or 1 rare card.

Barbarian Bowl

• Donating: 2 common cards or 1 rare card.
• Asking: 10 common cards or 1 rare card.

P.E.K.K.A's Playhouse

• Donating: 4 common cards or 1 rare card.
• Asking: 20 common cards or 2 rare cards.

Spell Valley

• Donating: 4 common cards or 1 rare card.
• Asking: 20 common cards or 2 rare cards.

Builder's Workshop

• Donating: 4 common cards or 1 rare card.
• Asking: 20 common cards or 2 rare cards.

Royal Arena

• Donating: 6 common cards or 1 rare card.
• Asking: 30 common cards or 3 rare cards.

Frozen Peak

• Donating: 6 common cards or 1 rare card.
• Asking: 30 common cards or 3 rare cards.

Jungle Arena

• Donating: 6 common cards or 1 rare card.
• Asking: 30 common cards or 4 rare cards.

Hog Mountain

• Donating: 8 common cards or 1 rare card.
• Asking: 40 common cards or 4 rare cards.

Legendary Arena

• Donating: 8 common cards or 1 rare card.
• Asking: 40 common cards or 1 rare cards.