just deserts - Wiktionary, the free dictionary

• (Received Pronunciation) IPA^(key): /dʒʌst dɪˈzɜːts/
• (General American) IPA^(key): /dʒʌst dəˈzɚts/

just deserts pl (plural only)

1. (idiomatic) A punishment or reward that is considered to be what the recipient deserved.

   It may appear that they're getting ahead by cheating, but they'll get their just deserts in the end.

• Deserts here is the plural of desert, meaning “that which one deserves”. Desert is now archaic and rarely used outside this phrase.
• The spelling just desserts is non-standard. It is sometimes used as a pun in, for example, restaurant names.

• payback, poetic justice, comeuppance, just rewards

• desert principle
• have it coming
• serve someone right

• “'Just Deserts' or 'Just Desserts'?”, in Merriam-Webster: Grammar & Usage, 2019 May 29