As per the ATP rule book a player is entitled to one (1) toilet break during a best of three set match
2 toilet breaks a best of five set match.
In addition,the toilet breaks should be taken on a set break and can be used for no other purposes.
It does not specify any time limit for the break.This is when I feel it is up to the Umpire who is apparently in control of the match,should make sure that any player is not 'exploiting the time' it takes for a toilet break.
In the match Tsitipas vs Murray,Tsitipas took a eight minute toilet break before the start of a decisive fifth set against Murray.Murray viewed as 'stalling tactics".
Of course a toilet break helps a player mentally by collecting their thoughts..Also an 'extended toilet break can prove detrimental for a player waiting for his opponent to come back and disrupt his momentum.
I would also like to say this is not the first time Tsitipas has taken extended toilet breaks,quite frankly it is getting to a point where commentators are actually timing his breaks now, again I find totally embarrassing at this level,like they did in his match again earlier against Mannarino,if that is not exploiting the toilet break to his advantage I do not know what is? Sasha also complained to the umpire in their final match at Cinncy,though he is allowed to get away with it,time and time again,maybe this serial behavior could be classed as 'unsportsman like conduct' where there is a penalty.