The Estonian government restricted flights to Estonia to depart from a few European cities. There seems to be a blanket policy of not awarding EU261 compensation if the airline can cite covid.

from Tallin Airport website.31.08.2020

• Berlin (EasyJet, AirBaltic)*
• Dusseldorf (Ryanair)*
• Edinburgh (Ryanair)* 
• Frankfurt (Lufthansa)* 
• Helsinki (Finnair) 
• Copenhagen (AirBaltic)* (from 02.09)
• London (AirBaltic, Ryanair, EasyJet)* 
• Milan (Wizz Air, Ryanair)*
• Minsk (Belavia)*
• Oslo (Norwegian, Air Baltic)
• Paphos  (Ryanair)* 
• Riga (AirBaltic)  
• Warsaw (LOT)* (from 01.09)
• Vilnius  (AirBaltic)  

and then changed

04.09.2020

• Berlin (AirBaltic)* 
• Dusseldorf (Ryanair)* 
• Frankfurt (Lufthansa)*  
• Helsinki (Finnair)  
• Copenhagen (AirBaltic)* 
• Stockholm (Air Baltic)*
• London (AirBaltic, Ryanair, EasyJet)*  
• Minsk (Belavia)* 
• Oslo (Norwegian, Air Baltic) 
• Paphos  (Ryanair)
• Riga (AirBaltic)   
• Warsaw (LOT)* 
• Vilnius  (AirBaltic) 

The Government of the Republic decided to extend the restriction of routes departing from Estonia to and arriving in Estonia from countries with high risk of corona infection also to fall and make exceptions to Warsaw, Copenhagen, Frankfurt, Riga, Helsinki and London, which will be kept open regardless of the infection rate in the country.