Ist not ißt!
Anytime I accidentally miss off the t from ist when typing, which I tend to do far too frequently then don't notice until too late, it marks it wrong and tells me that I should have used ißt! Surely this is an error and ißt/isst refers only to 'to eat'?
you are right. "ist" -> "it" but "isst" -> "to eat".
Ich esse / du isst / er,sie,es isst / wir essen / ihr esst / sie essen
It in an irregular verb. You can look up the hole table on https://dict.leo.org/englisch-deutsch/essen. If you click the "book"-icon right before "essen" you get the table.
I hope that was a little bit helpful.
best regards Angel