Usually, there are many people, but this year, there were fewer people.
Usually, on the last day of October, there are many people dressed up for Halloween in Shibuya. However, there were fewer people this year, because authorities urged people to avoid Shibuya during the Halloween season.
こんにちは!
ご質問ありがとうございます。
『いつもは多いけど今年は少なかった』は、
いくつか言い方が考えられますが、ここではシンプルに
Usually, there are many people, but this year, there were fewer people. と言えます。
『いつもハロウィーンの日は仮装の人が多いけど、渋谷ではコスプレをして集まるのは禁止されてたから今年は人が少なかったよ』は、
Usually, on the last day of October, there are many people dressed up for Halloween in Shibuya. However, there were fewer people this year, because authorities urged people to avoid Shibuya during the Halloween season. として
『通常、10月最終日は、ハロウィンのために着飾っているたくさんの人たちが渋谷にいますが、ハロウィンの時期は渋谷に近づかないようにとの呼びかけにより、今年はいつもよりも人が少なかったです。』と説明できますね!
メモ
urge someone to ~するようにせき立てる・促す
参考になれば幸いです。
You always used to see a lot of people wearing costumes on Halloween in Shibuya, but there weren't many people dressed up this year because they weren't allowed to.
この場合、次のような言い方ができますよ。
ーYou always used to see a lot of people wearing costumes on Halloween in Shibuya, but there weren't many people dressed up this year because they weren't allowed to.
「以前は渋谷でハロウィーンに仮装をしている人をたくさん見かけたが、今年は禁止されたので仮装した人があまりいなかった」
ご参考まで!