Substitute Dele Alli put Spurs ahead from the spot before Mamoudou Karamoko curled past Joe Hart in added time to earn the Austrians a deserved draw.
Gareth Bale and Son Heung-min were also on target for a disjointed Tottenham.
“I think it’s a question of attitude, which I have experienced before even at Manchester United,” said Mourinho.
“I had a similar situation – we lost two matches away in the group phase.
“When we get into the knockouts and you get better opponents and more difficulties, the team faces matches in a different way.”
Asked what he had learned, Mourinho said: “Nothing new, really. The fact that the Europa League group phase doesn’t motivate some of the players, I knew it.”
Spurs were fortunate to head in at half-time level after Bale’s penalty cancelled out Peter Michorl’s opener in Linz.
Son slid a finish beyond Alexander Schlager to put Spurs in front but three goals in a dramatic final 10 minutes saw both teams take a point.
Johannes Eggestein levelled in the 86th minute and Alli thought he had won it from the spot two minutes later, before Karamoko’s 93rd-minute effort.
Spurs lost 1-0 to Royal Antwerp in Belgium in October and beat Ludogorets 3-1 away from home last month.
They are through with a game to spare but will need to beat Antwerp at home next week if they are to progress as group winners.
“Our team at home is a different team,” added Mourinho.
“When we go to Antwerp, to Ludogrets, to LASK, the stadium, the weather, the emptiness, the atmosphere – I have a feeling, which is not a feeling, it’s experience, that some of the players, they feel that they shouldn’t be here.
“But the contradiction on that, is that players like Son and Pierre [Hojbjerg], players starting every match, are the examples of the guys that it doesn’t matter where, doesn’t matter the competition, they are there. And they are there for the team all the time.”