Pakistan got it dead right this year Eid is today Monday Sep 21
UK, US, Saudia, Gulf States, Peshawar and Afghanistan all got it wrong IMO.....and I dare say not for the first time! Morocco and Oman also did not blindly follow Saudis and celebrated Eid on Monday as well. A very thin Shawwal moon was sighted in Pakistan on Sunday (shown on TV as well) which could NOT have been sighted anywhere-else a day before (Saturday) not least for the important reason that moonset was before sunset on Saturday.
It is possible that moon is not sighted due to various factors such as cloudy weather etc. (if moonset is after sunset), something that Islam also recognises, but from a scientific viewpoint it is impossible for moon to be sighted if moonset is before sunset
Moonsighting for Shawwal 1430
Saturday Sep 19
Sunset: 7.06 PM
Moonset: 6.51 PM
Sunday Sep 20
Sunset: 7.04 PM
Moonset: 7.09 PM
In reality most mosques in the UK and US follow KSA since they do not have all the means (or so they claim) of reliably sighting the moon