It's Streak bonus reward from daily reward system:
Picking up your reward on a daily basis increases the counter of your reward streak. As your streak grows, you gain access to special bonuses in addition to your rewards. The bonuses are unlocked during the first 3 (Free Accounts) or 7 (Premium Accounts) consecutive days of taking rewards and stack with each other, staying available until your reward streak is reset.
As bonus you can get:
- No bonus for the first day.
- Allow hitpoints regeneration
- Allow mana regeneration
- Stamina regeneration (Premium only)
- Double hitpoints regeneration (Premium only)
- Double mana regeneration (Premium only)
- Soul Points regeneration (Premium only)
TibiaFandom - link
You can see all your bonuses under your equipment:
Also basic regeneration speeds are the same as if you were regenerating in regular situations, for example outside protection zones for hitpoints and mana, staying offline for stamina and killing creatures for soul points. The double hitpoints and mana bonuses also applies to regenerating equipment such as Soft Boots, which makes it a good way for mages to train their Magic Level for a low cost (the soul points regeneration is fast enough for that).