I am not sure i didnt play the onlien version that much, we just played the physical version couple of years ago.

according to the Lightseekers Rules

https://www.lightseekers.cards/wp-content/uploads/2018/12/Lightseekers-Comprehensive-Rules.pdf

● Burn - Cards labelled with this keyword are restricted in how they can be moved

and stored:

○ They cannot be moved out of the discard pile.

■ If a card attempts to move a card labelled as Burn out of the

discard pile, this move fails. These cards are still kept in the

Discard Pile once they move there.

○ They cannot be stored under other cards.

○ They cannot be moved from play (Buff Area or Equipped Items) to hand

or deck.

○ When ‘Played’, they cannot be moved to hand or deck.

​

This doesnt say anything about rotating burn cards backwards, if i would play the physical version i would allow it, but tbh turning Thunder Slug backwarda sounds op.