Saying 'je suis fini' in French is a big mistake and should be avoided. Instead, choose one of these past tense verbs explored here.
French Grammar Book - Ferndown Middle School
Je suis fini
Omitting French Auxiliary Verbs - Lawless French Grammar
Je Suis Intéressé(e) Dans French Mistake
In French, why is 'j'ai' sometimes used instead of 'je suis'? I thought 'j'ai' meant 'I have', not 'I am'. - Quora
Passé composé ⚙️
The ultimate guide to the passé composé (and a handy rule)
Applied Sciences, Free Full-Text
Impossible N'est Pas Français
Innocent Words That Are Bad In French
Don't even need to be able to speak French to understand this : r/shortguys
C'est fini! The Google Doc of the 100 Most Common English verbs translated and conjugated to French! : r/French
French Past Perfect - Lawless French Grammar - French Pluperfect
Thanking in French - Merci et Les Autres Remerciements