Perera was suspended during Sri Lanka's tour of New Zealand last December, after a laboratory in Qatar, accredited by the World Anti-Doping Agency (WADA) said he had produced a positive result in an out-of-competition test.
But the International Cricket Council (ICC) lifted the suspension with immediate effect late on Wednesday when it described the test as "an atypical finding" that could not be construed as evidence of doping.
"Before this tour he would have been in the T20 World Cup, opening up with (Tillakaratne) Dilshan, which would have been a huge advantage," said Sangakkara, now retired from international cricket and playing for English county side Surrey.
"I'm extremely confused as to what's happened. The labs in Qatar came back with an adverse finding in one of his urine samples and they named him, with the steroid that was found. Suddenly, over the last two days, they've withdrawn that and said 'we might have made a mistake'.
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"But the sad fact is that, I think, when you are provisionally banned, you can't even train or use the facilities that international teams use."
Sangakkara added: "Unfortunately, Sri Lanka have lost a remarkable player for quite a long time now and hopefully he'll have a very successful career from here on in."
Sangakarra, one of the outstanding batsmen of his generation, retired from the international game last year with a superb record of 12,400 runs at an average of more than 57 with 38 hundreds.
Last month, he scored 171 for Surrey against Somerset at The Oval in the County Championship.
But the 38-year-old left-hander, appearing on a platform with England pacemen Stuart Broad and Steven Finn, said he had no regrets.
"I thought I might miss it more, but I am quite at peace with the decision I've made.