Then the end of those who did evil was the worst [consequence] (30:10)

﴿ثُمَّ كَانَ عَاقِبَةَ الَّذِينَ أَسَاءُوا السُّوأَىٰ أَن كَذَّبُوا بِآيَاتِ اللَّهِ وَكَانُوا بِهَا يَسْتَهْزِئُونَ﴾
[ الروم: 10]

30:10 Then the end of those who did evil was the worst [consequence] because they denied the signs of Allah and used to ridicule them.

Then, the outcome of those who did evil deeds i.
e.
idolatry and sins, was an extremely evil outcome.
It was because they rejected the signs of Allah and would mock at and make fun of them.

Then evil was the end of those who did evil, because they belied the Ayat (proofs, evidences, verses, lessons, signs, revelations, Messengers, etc.) of Allah and made mock of them.

phonetic Transliteration

Thumma kana AAaqibata allatheena asaoo alssooa an kaththaboo biayati Allahi wakanoo biha yastahzioona

Abdullah Yusuf Ali - Translation

In the long run evil in the extreme will be the End of those who do evil; for that they rejected the Signs of Allah, and held them up to ridicule.

Safi-ur-Rahman al-Mubarakpuri

Then evil was the end of those who did evil, because they denied the Ayat of Allah and made a mockery of them.

Page 405 English transliteration